1. Lift Weights. It's important to maintain your muscle mass and lifting weights counters the slowing metabolism that comes with midlife. Cardio alone won't do it for those of us over forty.
2. Do sit-ups. Having firm abdominal muscles help maintain the length of your spine so you don't dip forward or get a "hunch" at the top of your back.
3. Get started now -- regardless of your age! Now's the time to workout, even if you're in your 70's or 80's.
A resource to check out is Dr. Pamela Peeke's book, "Fight Fat After Forty" which can be found on her website at http://www.drpeeke.com/?FFAF. You can also be re-directed there by clicking on the title of this blog post.