Volunteer for something (that's me as a cub scout leader on the left), it will add purpose and meaning to your life. Often when you retire after working for years, you feel let down after spending your entire adult life going to work. You miss your friends and the interaction at work, the feeling of accomplishment that sometimes defines us as a person.
I've always found at every job I worked, no matter how valued an employee I was or the contribution that I thought I made to the place-within a few years of leaving that job, I was forgotten. That's when I realized that the only job where your contribution continuing to matter is at home with your family. You can never be replaced there. But sometimes being at home 24/7 with a newly retired spouse can be challenging. There's such a thing as too much togetherness.
Try to volunteer for some outside organizations. There are many: hospitals always need help, homeless and women's shelters, food banks, schools love mentors to help individual students with literacy, libraries offer free ESL English as a second language programs, local historical organizations and museums always need docents, etc. There's probably not any church, scouting, club, group or place in your town/city that couldn't use your special contribution. Check out your local Sr. Citizen's center and newspaper for opportunities to make a difference.
Look at my best friend Gittan's son's blog, Hans lives in Sweden, is LDS and father of five, and doing volunteer work for a school in Kenya. You too can make a difference.
Question to comment on, tell us about some volunteer experience you've had: