There are men of wisdom. Do a little regularly and get fit the sensible way. It's coming along nicely isn't it and rewarding to see.
At least you have the winter to get it in order with manure, compost or whatever turned in and compost heaps started with whatever offerings you can round up.
Oh and time to get the shed sorted so that you have a place for a seat and a flask of tea!
You're unlucky though. I inherited an old garden seat so had somewhere to sit in the sun for starters.