Like many things in life, exercise could help you and it could hurt you–if you don’t do it properly. Here are some common pitfalls to avoid:

Skipping workouts
Sometimes you just don’t feel like it. Sometimes you’re simply not in the mood. Skipping workouts “just because” can set you back, especially if you’re on an exercise program. Not only does it make it harder for you to reach your goals—such as losing weight, building muscles, etc.—you could lose some progress you’ve made.

Eating right before a workout
If you eat a meal within two hours before working out, your body will be digesting that food and blood won’t flow as well to your muscles. This could also affect your post-workout recovery and lead to cramps. Instead, try a light snack.

Not warming up
Your body needs the warmup to raise your body temperature and get your blood flowing to help loosen up your muscles.

Holding your breath
It goes without saying that breathing is important. Holding your breath limits the amount of oxygen coming into your body. When working out, you might hold your breath without even knowing it.

Ignoring your limitations
Sometimes we get gung-ho and try to do more than we can handle. One, you could get hurt. Two, you usually sacrifice form and technique, in which case you’re just wasting time and energy. Know your limitations and attack them strategically and methodically.

Being too competitive
This is related to the above. Sometimes we can’t help comparing ourselves to other people and we try to keep up with them out of pride, ego, competitiveness, or just immaturity. Stay within yourself and focus on your goals.

Doing only what you like
You’re going to like some exercises better than others. That’s natural. But working on only what you’re comfortable with—usually it’s what you’re good at—will limit your range. In lifting weights, for example, you need to work all muscle groups. If you’re always targeting only the same muscles, you’re making it hard to them to recover and you’re going to look lopsided. Get out of your comfort zone once in a while. That goes for working out and in life.

Not hydrating
Perhaps the most common mistake is not taking water breaks. Hydration is important for cooling off your body and keeping your blood flowing. The guideline is 6 to 8 ounces for every 15 minutes you’re active, and then some more once you’re done.