It may sound like a cliche, but when it comes to strength training, it’s true:  No pain, no gain. If you work your muscles appropriately, they should have to repair themselves (and grow stronger) after you workout. And that means you’ll experience soreness.

Unlike excruciating or debilitating pain, a bit of post-workout soreness is a good thing. It means you’ve trained your muscles to exhaustion—traumatized them, in fact, by causing microscopic muscle tears. When your body repairs these tears, it reinforces the muscles, increasing your muscle mass and making you stronger.

Creating tiny tears in your muscles, of course, will cause you some pain and discomfort. You must, however, learn the difference between the normal pain that occurs when you work your muscles to the point of failure during strenuous exercise and the “bad” pain that occurs when you push yourself to the point of injury. Pushing yourself so hard that you hurt yourself won’t make you stronger faster. On the contrary, it will impede your progress by putting an end to your workouts—at least temporarily.

How can you tell “bad” pain from “good” pain? When you’re doing repetitions as part of your strength training routine, the first few should be fairly easy to perform. By the last few reps, however, you should be struggling. If you’re struggling from the outset, slow down and lighten up. You’re pushing yourself too hard and could cause injury.

The next time you feel sore after a good workout, be happy. The pain that makes you groan is also making you stronger.