When you think of strength training, you might picture that corner of the gym you actively try to avoid — where the free weights, barbells and squat racks live. But strength training, also called resistance training, isn't just for weightlifters and fitness buffs trying to build an impressive set of muscles. It's for everyone.

In fact, the U.S. Department of Health and Human Services' Physical Activity Guidelines recommend adults do muscle-strengthening activities two days or more per week.

You're not alone if you're surprised to learn that the guidelines include more than the 150 minutes of aerobic activity per week we're used to hearing about. Almost half of us meet those recommendations, but only 30% meet the ones for strength training, according to the CDC.

"If you don't use it, you lose it," says JJ Rodriguez, a clinical exercise physiologist at Houston Methodist. "We've known for a long time that resistance training is important, but what we're finally starting to see through research is that it's a prime predictor of a person's health, particularly mobility, as they age."

The benefits of strength training are rooted in how it counteracts sarcopenia, the muscle loss and joint tissue wasting that naturally happens with age — something we should all be trying to prevent.

"That decline begins as early as around age 30," warns Rodriguez. "But resistance training is one of the ways to slow this process down and even hinder it completely. The tricky part is that it's still very foreign to people."

What is resistance training?

"A really simple way I like to describe resistance training is any activity that the body has to overcome," says Rodriguez. "That means getting up out of your chair is, in essence, a form of resistance since your body is opposing gravity."

Noting the person-by-person variability in strength training, Rodriguez acknowledges that the load engaged just by standing isn't enough for most people to reap a health benefit. But he adds that even this simplified visual helps explain what resistance training is and how it benefits the body.

When your muscles, bones and joints take on a challenging load, it promotes tissue turnover and maintenance. We see this most obviously as muscles build and tone, but resistance training isn't just about muscles.

"It also helps bone and joint health," says Rodriguez. "Since your muscles are connected to your bones, any load they experience also creates pressure on the bone. This has a stimulating effect on bone maintenance and growth."

The simple example of getting out of your chair serves another purpose, too. It highlights why anyone can benefit from strengthening their muscles.

"When you hear the terms deadlifts and lunges, you think of athletes," explains Rodriguez. "But the reality is that we all do some version of these movements every single day. A deadlift is picking up your groceries. Lunging is getting up off the ground."

Rodriguez adds that a primary reason people throw out their backs doing everyday activities is "a lack of muscle performance." That can be improved with strength training exercises.

How much resistance is needed to truly challenge your body and reap the benefits of strength training? Rodriguez says that is hard to quantify.

"It's variable," says Rodriguez. "It's not like aerobic exercise where we have a quantified amount we recommend to all adults. The most important piece of resistance training is the load on the muscle, but what that looks like for you might be different from someone else."

For instance, doing five reps of a sit-to-stand exercise might be challenging for a person who's frail or deconditioned, but wouldn't require a lot of physical exertion from people who are already in good shape. They'd benefit from more challenging bodyweight exercises, resistance bands and weights.

How to start strength training exercises

Adding resistance training into your workout routine may sound daunting at first, but Rodriguez points out that strength training workouts can actually be easier than aerobic ones.

"You're not always breaking a sweat, the exercises are often easier on the joints and sometimes you may not even feel like you did a workout — yet there's benefit," says Rodriguez. "The tricky part is the learning curve that comes with strength training."

Since many people don't know what to do, it's easier to just go for a walk or run and track your steps along the way. But, again, you're missing out if all you do is cardio.

Here are Rodriguez's tips for those looking to start strength training exercises:

1. Remove any mental and emotional barriers

One thing Rodriguez cites in the exercise literature are the known stigmas associated with resistance training. Since these stigmas can easily derail even just the intention of doing more muscle-strengthening activities, they're the first things that needs to be addressed.

"There's the learning curve barrier," says Rodriguez. "People don't do it because they don't know what to do. Their doctor is recommending resistance training, but they don't have any resources — no gym, no trainer. Emotional barriers seem to weigh just as high: 'How will I look at the gym?' and 'What will people think of me?'"

How to overcome such barriers? Here are some tips from Rodriguez.

2. Begin with these three simple movements

Before you hunt for the best deal on a gym membership or set of dumbbells, know that your body weight itself can be used to function like a great piece of equipment.

Three bodyweight-based resistance exercises that Rodriguez recommends to anyone are the:

• Push up
• Plank
• Squat

"You're going to benefit from some version of these exercises no matter who you are," says Rodriguez. "There are lots of phases and variations to each, and they can be made easier or harder based on your fitness level."

For instance, a squat can start as a simple sit-to-stand exercise, progress into a full squat from a standing position and eventually culminate in a weighted squat.

"You can also do three to five sets with a bunch of repetitions, or you can do just one set," says Rodriguez. "In fact, there's really good literature to show that frail individuals show improvement in muscle function and growth with just one set."

Each of these exercises simultaneously targets multiple major muscle groups — chest, back, arms, core, legs — more closely mirroring how your muscles get used in your daily life than, say, a crunch, which only works your frontal abdominal muscles and typically doesn't address the core muscles that wrap around your lower back.

Doing these more functional strength training exercises can help build multiple muscle groups as well as help coordinate how they move together as you go about your daily activities.

All three are also fairly simple to learn and master at home — so if your goal is eventually to make it into the gym, you can do so already feeling comfortable with a few key exercises.

3. Try weight machines if you have a gym membership

"If you have access to a gym, weight machines are an easy way to get started outside of the body weight exercises we just mentioned," says Rodriguez.

The advantage of starting with weight machines is that free weights require a lot to control. Form is critical when using dumbbells or barbells, and movement patterns are important when using resistance bands.

"There's really only one direction a weight machine can move when you're using it, so it's hard to mess up," explains Rodriguez. "It's also fairly intuitive to know when it's time to add more weight as you get stronger over time."

4. Know how and when to bump up the load

Muscle-strengthening will look different for everyone, but as your body gets stronger, your exercises will need to become more challenging, too.

"The biggest piece is to increase volume over time," says Rodriguez.

There's an equation for that: Sets X Reps X Weight = Volume.

"Muscle strengthening requires increasing at least one of these variables, and changing each individual one gives you a different muscle outcome," explains Rodriguez. "For instance, maybe you want to tone your muscles, which requires a higher rep range of 10 to 15 reps — the number of times you perform the movement per set. Or maybe you want to strengthen your muscles, so you increase the weight but only perform 6 to 8 repetitions."

When is it time to actually ratchet up your load?

Rodriguez adds that you want to finish with your muscles feeling challenged, but not totally fatigued.

For instance, if your goal is to do 10 reps and, when you get to the end, you feel confident you could do more reps with ease, you're likely ready for more weight. But if the last rep or two are still a struggle, maintain that same volume for another week.

When you're ready, Rodriguez says, gradually increase your weight by five pounds about every two weeks.

5. Try an app or find a trainer

If you still aren't quite sure where to start or what to do, Rodriguez recommends trying a fitness app or finding a trainer. Many apps, both free and subscription services, can build bodyweight workouts for you or offer guided exercises using equipment you might have at home.

"If you're looking to improve or learn exercises, a trainer can help you make a plan and carry it out," says Rodriguez. "The most important thing is to find a trainer that listens to you and that you feel comfortable with. I recommend shopping around for trainers. If you have an appointment and it's just not a good fit, move on."

He recommends starting with the American College of Sports Medicine's ProFinder tool, a database that only lists individuals who maintain active ACSM certification.