If you dread your workouts, you may not be getting all of the benefits for which you’re torturing yourself. A number of studies point toward an inverse relationship between exercise benefits and the psychological stress associated with being forced to exercise.MORE: How to Fall in Love With FitnessThe studies, using rats, make a distinction between voluntary exercise and forced exercise. In voluntary exercise groups, the rats engage in “free wheel running.” They have running wheels in their cages, and they can get on and off at will and run at whatever speeds suit them. They exercise when and how they want to. The forced exercise groups engage in “forced treadmill running.” This training requires the rats to run when, how long and how fast the experimenters choose. They often have to be prodded using negative stimuli.The result? As you might expect, both groups burned calories and improved fitness levels. However, differences appear in psychological behavior outcomes and in neurological, endocrine and immune system function.For example, the forced rats displayed more anxiety and were less likely to explore new environments. In contrast, voluntary free wheel running reduced behavioral depression and learned helplessness that often accompanies exposure to stress. Learned helplessness behaviors in rats resemble the behaviors of people suffering from anxiety and depression. They respond to situations with exaggerated fear and fail to escape stresses from which they could normally remove themselves. Voluntary exercise minimizes or even prevents these depression behaviors.MORE: Bust a Bad Mood With ExerciseVoluntary exercise is also more effective than forced exercise in promoting healthy neurons (nerve cells) in the brain and in enhancing the recovery of movement after a stroke. A 2011 animal study examined the effects of voluntary versus forced exercise on Brain-Derived Neurotrophic Factor (BDNF) and motor recovery. BDNF is a growth factor involved in preserving and forming nerve cells and is critical for learning and memory. In this animal study, rats who had suffered strokes underwent rehabilitation that involved physical exercise. The rats in the voluntary exercise group improved their movement deficits significantly more than those in the forced exercise group. They also had significantly higher levels of BDNF than the forced exercise group.Yet another animal study looked at the effects of voluntary exercise on the ability to deal with acute stress. Rats engaged in either voluntary running or no running for a period of four weeks. Those in the voluntary running group showed less behavioral depression and no suppression of the immune system in response to acute stress. Those in the sedentary group took longer to recover from behavior depression and had immune system impairment.Clearly, links exist between positive exercise experiences and positive health effects. There are also ties between negative exercise experiences and negative health effects. Some negative effects may come from the physical stress of the activity, such as exercising for too long, too often or too intensely, or from the type of activity itself. Others may stem from psychological stress. While none of us are “forced” to exercise in the same way rats are (unless you have an unusually aggressive and innovative personal trainer), many of us do indeed feel like we force ourselves to exercise, using negative motivation such as thoughts of having a heart attack, getting diabetes or becoming even heavier if we don’t get on that treadmill. Or we may simply stick to our dreaded program, because we made a commitment to do it and that commitment is all that’s keeping us going… otherwise we’d be failures, right? It’s all stress, stress, stress.MORE: How Reducing Stress Can Help You Weigh LessNow some pointers. To make the physical stress of your workouts positive and not negative, keep the duration, frequency and intensity at lengths and levels that make you feel good and energized. If your program saps your strength and energy for the rest of the day or the next day, you’re likely exercising for too long or too hard. If your exercise seems to disrupt your sleep routines, change the duration, intensity or the time of day that you exercise. If you hurt after exercising, decrease the duration or intensity and make sure you are using the correct form or exercise technique. If those changes don’t help, it may simply be the wrong activity for you. Try a different one.Now for the psychological stress. Try, try and try again to find something you look forward to or at least something that doesn’t give you “the dreads.” Two of the largest obstacles to exercise enjoyment are the activity choice itself or the intensity of the activity. Choose an activity you enjoy. If you like to dance, take an actual dance class or try Zumba, BodyVive or another aerobic dance class. If you can’t leave the house, work out to a DVD. If you like to play basketball, join a league or find a place to play pick-up games. If you like to walk, then walk. Don’t feel like you have to run. Walking is great exercise. You don’t need to push harder than is comfortable for you. Lots of happy walkers have turned into unhappy joggers.That brings us to the intensity point. When you have an activity you enjoy, do it at an intensity you can at least happily tolerate. If you don’t like the sensation of pushing yourself hard, don’t do it. You will dread it, and you will likely stop altogether. Or if you don’t stop, your commitment alone will keep you going, and you’ll embody that forced exercise mentality that may rob you of some health benefits… both emotional and physical. Better to go a little longer and enjoy the sensation of moving. You may also try some intense but short bouts, i.e. interval training. These can deliver high fitness benefits and be easily tolerated by even intense-averse people. The ultimate goal is to reap all of the health benefits exercise can provide and enjoy the process of getting them at the same time.MORE: Get Fit in Less Time