If you are new to exercise, start with conventional cardio for about 3 months, then circuit training for another 3 months to build up your fitness level. (homefitnessguru.net)
He's at the last stage of building up his fitness and he's not far away. (arsenal.com)
The longer that lasts, the more time you have to dedicate to build up his fitness again because he has been out for four weeks. (arsenal.com)