The cure for overtraining is very simple: Rest.
Your body needs rest after lifting weights to allow your muscles to recover and grow. When strength training, don't work the same muscle group two days in a row. Allow at least one day of rest before working the same muscle group again, more if you're lifting very heavy weight.
For cardio, you may be wondering if it's okay to do it every day. That will depend on your intensity and the activity you're doing. It's not a great idea to do the same workout everyday as that can lead to both overtraining and repetitive stress injuries. You also shouldn't do intense and difficult workouts, such as high intensity interval training every day of the week, since that will also eventually cause problems.
If you want to exercise every day, go for it. Just make sure you work at a variety of intensities to work different energy systems and avoid overloading any one energy system. For example, if you usually run and bike every day, try light walking or swimming on other days. These 'recovery' workouts will help you stay fresh and the cross-training will help you avoid injuries.
Doing too much too soon can also lead to overtraining and injuries. If you're a beginning runner, don't attempt to run too much your first time out. Start with a walking/running program and slowly build up your running time each week. For lifting weights, you want to progress each week, but you don't want to add so much weight that your body can't handle it. There are a few other things you can do to avoid overtraining:
- Warm up before your workout. Proper warm-up can help prevent injuries.
- Fuel up after exercise. Your body needs energy to recover and that comes from food. A combination of carbs, protein and fat will give your body the energy it needs. Check out About's Nutrition site for more detailed information about balanced meals.
- Stretch. Tight muscles can often cause other muscles of your body to overcompensate, which can cause injury over time.
- Schedule recovery days into your weekly routine. Listen to your body. If you're 10 minutes into your workout and you're feeling tired and unmotivated, go back home and rest or do a light yoga workout.
- Get adequate sleep.
The most important thing you can do for yourself when you experience overtraining symptoms is to rest. It's better to take a week or so off from exercise and come back fresh than to permanently injure yourself. Even a week or two isn't enough to completely lose your fitness and you may find you come back with more energy than ever.