Congratulations on your new bike and great job in starting to achieve your health goals! I think you're off to a good start doing the low impact/advanced beginner classes. Once you progress (those workouts start to seem pretty routine for you), I highly recommend moving to intervals, HITT, tabata. You can get a much more efficient workout in less time doing intervals, but it's important that you don't cheat with interval training; push yourself to the max for full effectiveness. The great thing about HITT/intervals is that it revs up your metabolism, so even after you're done working out, your body is still burning calories at high state. On stretching: I stretch after every workout - so important for recovery and to reduce soreness. Even if for just 5 mins. Eventually you will want to add strength/weight training, but take it one day at a time.... For cycling workouts: when I want to really push myself, I go with Alex. T. If I want to go hard, but not to the max, I like riding with Emma L. If I want more "leisurely" rides, but still a really good workout, I go with Dennis M. or Christine D. Stretching, I am a big fan of Chase T. and Dennis M.