There is no question there's an obesity epidemic in the United States. And many professionals in the health and fitness industry are encouraging people to exercise to lose weight. However, people often mistakenly associate exercise with weight loss exclusively. In reality, the decision to exercise is a personal one and there are hundreds of reasons to work out that don't include weight loss. So if you're looking for a few alternative motivators to embark on an fitness regimen, here are five reasons to exercise that have nothing to do with weight loss.

1.  Increase Lean Muscle Mass
Even if you aren't overweight, without lean muscle, your body still has fat. The best way to build metabolically-active lean muscle mass is to exercise with a combination of cardio and strength training.

Maintaining lean muscle mass improves metabolism and builds bone density. It can also strengthen the immune system, pulling from protein reserves to fight infection.

Finally, lean muscle mass can help reverse insulin resistance, the body's ability to process excess glucose in the bloodstream. More insulin in the blood causes a rise in blood sugar, which can lead to Type 2 Diabetes. Lean muscle mass counteracts this process so the body can efficiently rid the bloodstream of excess insulin.

2. Reduce Blood Pressure
For those prone to high blood pressure, or hypertension, exercise can help lower blood pressure. Physical activity strengthens the heart so it can pump blood with less effort and strain on the arteries. Not to mention, exercise helps with weight management, which also controls blood pressure.

If you have already been diagnosed with high blood pressure, keep in mind that weight training may cause a temporary spike in blood pressure so it's important to speak with your doctor before starting a program. However, there are still ways to strength train safely to counteract the short-term spike and reap the long-term benefits of lower blood pressure. For some people, consistent exercise can even take the place of medication to control blood pressure. 

3. Decrease Stress
If you think you're too busy to exercise, exercise may be just what you need. Engaging in physical activity increases endorphins, the hormones produced in the brain that create a "feel good" effect. Exercise also acts as a form of meditation to distract you from the daily stressors in your life. Over time, you may begin to feel more clear-headed and relaxed on a regular basis.

4. Prevent Injury
If you've ever experienced a strain, break or tear, you know that these injuries typically happen in parts of the body that are weaker or more imbalanced than others. Rehabilitating such injuries means strengthening the surrounding area.

Weak muscles are more susceptible to injury because of their inability to handle the demands placed on them — both from everyday activities and during exercise itself. Stronger muscles means more resistant tendons, ligaments and bones.

Equally as important is exercising safely to prevent injury.  Start slowly and focus on form while increasing weight over time. Rest your muscles appropriately between workouts, warm up before each workout and stretch to maintain flexibility.

5. Better Sleep
The energy you expend doing physical activity promotes better sleep in several ways. Exercise raises the body's core temperature and when it drops post-exercise, that induces sleep. Additionally, those who suffer from insomnia and other sleep disorders may find that the decrease in stress and anxiety from exercise allows for better sleep.

Exercising regularly not only improves sleep quantity, but also sleep quality by increasing the amount of time spent in deep sleep. A deep, restorative sleep will strengthen the body's immune system.

But beware that exercising too close to bedtime may have the opposite effect and increase energy or disrupt sleep. Likewise, exercising too much, or overtraining can also make sleep more difficult.

Brian Maher is the owner of Philly Personal Training, a Philadelphia-based studio offering personal training, physical therapy, and nutrition counseling. Philly Personal Training is the only studio or gym in Philadelphia that requires its trainers to possess a college degree in an exercise-related field, as opposed to a basic certification.