Swimming, too! If you can start swimming 2-3 times per week for 45 min+, this is a great cardio trainer. If you purchase some paddles ($15) then you have a great upper body/core workout. Plus, the GREATEST thing about incorporating swimming is it is low impact, something by 40+ body really appreciates. Then you get in 2-3 rides a week, as well as 2-3 treadmill w/strength training, you have a great week of cross-training.