I've been doing a spin session 3 days a week and find it quite addicting. I've been combining it with some running, swimming and lifting. The holiday softness is gone and I'm in the best shape I've ever been for the end of January. One thing that I think is really important is to use the off season to work on non-bike forms of fitness. This is the time to strengthen the areas of the body that don't get worked when riding. Developing those muscles now helps revent injuries down the line.