I'm the opposite. No gym for me, but all winter at home riding on a dumb trainer one day, rowing machine the next for 45-60 minutes, watching you tube training videos. Its not like outdoor cycling, more like intense spinning. Cardio is much more intense for me at home, just can't seem to get the heart rate up for as long while riding outside mostly alone, can't maintain the cadence. Maybe there's some security that I'm never far from home and I can push to the max . It's my legs that hold me back.