The Strange Cycle

I seem to be stuck in a repeating pattern of behaviour with regards to my exercise regime. I go for a bike ride, it makes me feel good, so the next day I go for a longer bike ride, then I over-do it and end up stiff and sore, then I have to have a few days of rest and recovery, then I start to feel better, then I get the urge to go cycling again but swear to myself I’ll take it easy this time and build up the distances gradually, then I go for a bike ride….. 
I seem to struggle to achieve moderation. I’m either over-doing it, or not doing it. It’s either flat out (on the bike) or flat out (on the sofa). 
So my question today (rather to me, than to you) is this: How can I re-train myself to stick to a sensible exercise program, instead of going round and round in circles and probably damaging my body rather than improving its fitness?
I’m sure Paul McKenna has written a book about it but I’d rather work it out for myself. 

RC 11-6-17