Do what you can my friend, and don't stop until you can't do it anymore.Im 56 with some health issues(Asthma, vascular, Achilles tendonitis) and I couldnt do a usual 30-40mile stint, or a 75miler. I would be utterly done in. The occasional day out of about 20miles return trip is about my limit, and i only use turbo on Bosch performance CX 85nm
So you must be doing better than me lol