One of the things that interests me the most is finding a purpose in life. For some it comes early, and they spend a lifetime building their life. For others, life just passes them by with inertia taking them along, school, job, marriage, kids, retirement. The good news is, if you find yourself thinking that life passed you by, the odds are that you can start now building your future. With people living longer (stay healthy) you can have a long and happy full life after the kids have grown up and moved on.
Just to give you a taste of what I have in mind, here is a video showing several things that retired couples can do to start a business.