You don’t have to train like famed U.S. runner Steve Prefontaine to get a boost from exercise, but you may want to mix up your workout.

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The mind-body connection is often cited as an integral component of happiness. Keeping the body fit through exercise has measurable effects on the mind, too. People who exercise generally have lower levels of anxiety and depression. But studies have also shown that the same genetic factors that motivate people to exercise might also make them less predisposed to being depressed, eliminating a causal connection.

Boosting happiness through exercise doesn't require a diehard devotion to fitness. Embarking on a less ambitious fitness regimen can help to keep your goals realistic while also producing tangible results. (No need to feel guilty about not reaching your exercise goals, which would only contribute to unhappiness.)

Exercising lowers the body's levels of cortisol, a hormone associated with stress. Depending on your stress level, you may need to alter your workout accordingly. If you're more stressed, it might take a longer, more rigorous workout to burn off cortisol and walk away feeling relaxed and refreshed.

You may have heard of endorphins. Exercise causes the pituitary gland to release these powerful, mood-boosting chemicals. As with cortisol, the release of endorphins from exercise varies depending on the person and situation. Intense aerobic activities, such as running, are more likely to release endorphins than light weight lifting. Experts also recommend varying workout routines and activities. Like bacteria that become resistant to antibiotics, the body builds up a resistance to the strenuous activities you put it through. Listen to music while working out, try a new activity, play a new sport, and above all, work hard, and that endorphin-produced "high" should come, along with many health benefits.