Midlife women often exercise for the two least motivating reasons, says 42-year-old psychology researacher Michelle Segar. They exercise (1) to lose weight and (2) to protect their health. Both really good reasons. Just not the most inspirational ones for this age group.

In one study of 156 women, 61 percent named these reasons as their top motivators -- and they happened to do the least amount of exercise. Here's why: Midlife women don't always lose weight with exercise. So if they work to shed pounds and it doesn't work, they get frustrated and give up. Regarding the health reason: Women who have a full schedule and generally feel healthy are not likely to fit in fitness.

What's the best motivator, then, for midlife women? To improve their state of well-being. Think better moods and less stress, and exercise might just become a priority.