Picking the appropriate weight for an exercise can be an intimidating task, but it’s also an important one. If you choose a dumbbell or barbell that’s too light, you’ll have to do a lot of repetitions to effectively work your muscles.

If you pick one that’s too heavy, you might strain a muscle or tendon or sprain a ligament. But pick just the right weight, and you’ll be able to fatigue your muscle with fewer reps. But how can you know which weight is right for which exercise?  Here’s the test: If your goal is to build muscular endurance, you should be doing 10-12 repetitions of an exercise. If you can lift the weight for more than 10-12 reps, it’s not heavy enough.

And if you can only complete fewer than 10 reps, then guess what? The weight is too heavy! It’s a very simple formula, but one that’s essential to follow in order to maximize the effect of every single rep.