If you have had a hard time working out consistantly over the years, what is one way to get you back on track?
Some people (yours truly included) do really well with daily to-do lists because there is something very gratifying about putting a check mark against an item. It is important, though, to start in a way that it is easy to accomplish and enjoyable to do until a habit is beginning to form.
I agree with LaRue that it should be SOMETHING daily initially, and I would even stretch the definition of exercise as long as all parts of the body are moving for a little while.
I also would suggest a self-reward for having stuck with an exercise program for a period of time.