I joined a gym around my 40th birthday and I'm now 46. I don't go as often as I should, but I keep going because:
1. I can eat more whenever I exercise. I don't have to starve myself to maintain or lose weight. In the Weight Watchers program, their point system even assigns points for exercise, so if I want a treat and it has 5 points, I can do 5 points worth of exercise.
2. Muscle burns calories better than fat. It looks better, too.
I look less lumpy, a little more streamlined when I work out regularly. I spend 30 minutes on the weight machines, use some dumbells, and work on both upper and lower body in that time. I then try to do 1 hour of cardio on the machines. Stretching to warm up before and cool down after is imperative.
3. Most evenings I work Med/Surg, I consider it "aerobic nursing" with the pace, the almost constant activity, and demands. Being in relative shape helps me to keep up, and I would like to continue my nursing career for as long as I can. I do stomach crunches to protect my back, less than for "looks" at this stage of my life. If I leave nursing, I can envision it will be related more to emotional/psychological burn-out rather than physical reasons, but I'll just have to see how the ole bod holds up.
4. All through the stress of nursing school, I used the phrase, "I will either cry it (stress) out or sweat it out" and I did both. But the exercise I did then and do now helps to keep me a bit more on an even keel and I almost always feel better afterwards.
5. You can do it, Mary, and others! Take it slowly to avoid injury and drink LOTS of fluids before and after. Be kind and patient with yourself and the benefits will slowly outweigh the temporary aches and the hassle of going to the gym. Vary your workouts (if it's nice outside, I take 1 to 1 1/2 hour walks rather than go to the gym, and they're so good for me, spiritually and emotionally), and get advice from the trainers there.