Over the years I have come across a lot of websites that have helped me with exercise. Since physical health is a part of provident living I figured I would share them with you. All of them are free, though they may cost for more features.
Live Strong will help you track what you eat and your exercise. It's the easiest site for doing this that I have used. If you run or walk it will allow you to put in a "loop" of what you have done, calculate the miles for you as well as elevation (to some degree).
Local Hikes - lists hikes that are in your area. It will give you a lot of information on how to get there, how long they are, best time to go and reviews.
While I haven't looked at the whole website I did find some great weight exercise guides on Shape Fit. One thing I like about this site is that it has a huge list of areas to exercise (abs, biceps etc.) and then lists exercises for each area including pictures to help you understand.
Want to try running a 5K? Try Cool Running. It will give you a program to run every week for 9 weeks. Remember that if you are more out of shape that walking may be better for you at first or at least don't be afraid to repeat weeks so that you can avoid injury.
Robert Ullrey did a series of podcasts (MP3 programs) to go along with couch to 5K. He starts you out, lets you know when to begin running and walking and includes music and encouragement.
Maybe you would just like to try walking. Check out walking.about.com for walking tips, mistakes, saving money etc.