“Lift heavy” is a popular approach to strength training these days. Backed by evidence, weight-bearing exercise has been proven to boost mood, aid in weight loss, build muscle that contributes to a faster metabolism, reduce symptoms of anxiety and depression, and improve sleep, as previously reported by TODAY.com. But how heavy should your dumbbells be exactly?

Lifting too heavy of a weight can lead to injury, and lifting too light might delay all the benefits strength training can offer. Get it right nearly every time with this trainer-approved evaluation.

Trainer Tip of the Day: Use This Test To Determine You’re Using the Right Weights

Assess the weight of the dumbbells by reaching for a weight you’re comfortable with, testing how fatigued you feel when using them and lowering or increasing the weight to challenge yourself to the point of fatigue, Stephanie Mansour, TODAY fitness contributor and personal trainer, told TODAY.com.

“Keep in mind that you may need to perform this test multiple times for different exercises since some muscles, like the glutes and hamstrings, can handle heavier weights while other muscles may require lighter ones,” she added.

Repeat this test every few weeks to continue challenging yourself as your body adapts and learns to better withstand heavier weights.

Why It Matters

Muscle mass increases thanks to a process called hypertrophy, when you challenge the muscle with weight so it adapts and grows.

Building on that challenge is how you get stronger, TODAY.com previously reported, so increasing the weight of the dumbbells you lift is essential. Be sure, however, to increase the weight gradually. “Lifting too heavy of a weight can lead to injuries such as fractures or dislocations,” Mansour said.

For specific guidance on how to progress your weight and repetitions over time, try this 4-Week Strength Challenge.

Weightlifting should be a part of a well-rounded lifestyle, too. Supplement it with adequate nutrition for muscle growth and effective recovery. Muscles grow while you sleep, so it’s vital you get enough.

How to Get StartedWarm up: To prime your body for weightlifting, be sure to warm up, said Mansour. “Stretching before exercising increases blood flow to the muscles and improves your flexibility and range of motion, decreasing your chance of injury,” she said. This 10-Minute Dynamic Stretch is a great full-body warmup routine. Perform 10 reps: Grab a weight you’re comfortable with, said Mansour, and perform 10 reps of the exercise you’ll use it for. If it’s bicep curls, for example, hold the dumbbell in one hand and do 10 curls.Assess difficulty: If you got through the exercise easily, increase the weight by two pounds. If you struggled about halfway through, decrease the weight by the same amount.Perform 10 more reps: During this next set of 10 bicep curls, pay attention to how the last five reps feel. “Are the last five reps challenging? If so, keep this weight. If not, increase the weight by a couple of pounds,” says Mansour.Perform 10 more reps: This final set should have you feeling fatigued, said Mansour. It should feel challenging all the way through. If so, you’ve found the right weight.

TODAY’s Expert Tip of the Day series is all about simple strategies to make life a little easier. Every Monday through Friday, different qualified experts share their best advice on diet, fitness, heart health, mental wellness and more.