Losing weight and exercising more seem to be goals atop many to-do lists. But why do so many good intentions fall by the wayside within weeks? Experts say the likely culprit is setting unrealistic goals that lead to stress and failure.

“It’s important to start small,” says Shona Vas, Ph.D., Cognitive Behavior Therapist at the University of Chicago. “If you never exercise at all, it’s not likely you’re going to run a marathon in two months. [Likewise] if you have no awareness of what you eat a good place to start is looking at the label for food content.”

Not reaching a goal sure can be disheartening, but it also could have far greater affects on your health than you realize. Researchers at the University of British Columbia, Vancouver and Concordia University, Montreal teamed up to investigate what happens when people set goals that they did not reach. They found that increased stress from unattained goals leads to elevated levels of CRP (C-reactive protein), a biological measure of inflammation. Over time, chronic levels of inflammation heighten the risk of many diseases including diabetes, osteoporosis, and heart disease.

Which is not to say, don’t set goals. Instead, keep them realistic and be flexible.

“It may be best to not think of goals as being written in stone,” says Michael F. Scheier, Ph.D. Department of Psychology Carnegie Mellon University, “One might have the goal of exercise for one hour, five times a week, but life circumstances might not allow this. Under these conditions, it’s better to scale back the goal to make it more achievable.”

Smart Goal Setting

Be specific and set observable targets, recommends Vas. For example, don’t set big goals like get in shape or lose 20 pounds in a month. Instead, translate what that means into what you’re going to do on a day-to-day basis. Anticipate your own personal challenges and have a plan to deal with those. If Tuesdays are filled with meetings and appointments, don’t plan to exercise on Tuesday.

“Exercise doesn’t always have to be at the gym,” adds Vas, “when you go to the grocery store, park at the far end of the lot. At work, take the stairs instead of taking the elevator.”

It’s also helpful to have support. That might be a personal trainer who will hold you accountable in the gym or a friend who will lend a supportive word to help keep you on your path.

Set your goals wisely and you’ll gain motivation and self confidence. Experiencing success, says Vas, creates and maintains your enthusiasm for the weeks and months ahead.