I can't really know what you would enjoy doing, but here is my pseudo-retirement plan(s) (in no particular order):
*apply to graduate school, see if I can get a full ride + stipend (to cover expenses) to get PhD. not holding my breath, but there is a small chance.
*teach high school science and math
*get a job with the BLM
*get a job with the national park service.
i tend to be more biased towards the options which include some type of pension.
what do you like to do? If your expenses are really $25k/yr, you shouldn't have a hard time covering that, unless flipping burgers is your passion.