I would mix in some treadmill with it start at a pace that makes you work but not so bad your out of breath (as in cant have a conversation) put 1"or 2" of incline, you wont really feel it but it helps. This cardio will help you with extended rides ( and with overall health) you will be amazed I started like you not that long ago and I weigh quite a bit more But with approx 60 days of treadmill 2 miles every day at a pace of 4mph 2" incline I can hold a conversation for a 28 mile ride no sweat.....well maybe some sweat
