For those that are really enthusiastic and have spending cash, you can even get computer program where you can go head to head with Tour de France riders or create your own riding partner. These are fine if you can handle the seat not being quite right. I prefer my rollers or stationary trainer since I can ride my own bike with my own seat. I am lucky to live just a five minute ride from a nice mountain biking area. Super for building strength and balance.
Most health clubs have regular spinning classes.
Be sure to get real running shoes at a real running shoe store. In the Twin Cities, I recommend Runner's Edge or Run N' Fun in St. Paul and Marathon Sports or Gear in Minneapolis. There is much more impact stress that can cause aches and injuries. Start by alternating walking and jogging until you can go for 20 minutes and then gradually add more jogging. The impact stress is much less than running and you can still get your heart pumping.