I ride a stationary bike 45 min every day,no days off i do 10 miles.Is that okay?I am 52 and wondering how much should i do.I want to take Karate and the course is twice a week for a hour each day.Seems this is not enough to learn anything,is it?I will get in the gym on the first of March to lift weights along with the bike work.Is this sane and okay.I am in fair shape.15 lbs over weight,other wise i am good to go.