I also take two mandatory breaks - as I told myself I am there not just to pedal, but also to enjoy the nature, so I sit for 10-15 minutes, eat, drink, talk to my wife on the phone, watch the river flow and birds dive for fish. That time does not count towards those two hours.
I guess you are retired? I can practically ride twice a week, Tuesday after work and then Saturday. I figure that gives me enough exercise so I can legitimately spend other evenings in my basement workshop. :)
