The main issue for me is keeping injury free. Have persistent issues with my right leg, with strains moving from my achilles, to my calf, to my hamstring and up to by backside (or butt). I have had some physiotherapy sessions, and my physio suggested that the problems are more related to my back (and sciatica) than my leg muscles. He gave me some exercises, though I’m not sure how effective they were, but I have a tree in my back garden with a strong horizontal branch at just the right height, and have found that hanging from this tree for as long as I can (usually after a run), typically 1 to 2 mins, seems to give some relief. I kid you not when I say that my height increased by about one centimetre after I started doing this (I had noticed a similar effect a few years ago following a manipulation session with my Pilates teacher). Had a bit of setback when I tried hanging from a pair of vertical poles when staying at an airbnb in Yorkshire, which created a sort of crucifix position. This did something bad to my shoulder and now I’m just able to tentatively return to hanging about seven weeks later.
The last three mornings I have played it safe and jogged around the local park, managing to build from 20 to 25 minutes, including occasion stretch stops. Need to multiply that by about ten to complete the marathon, so will need some patience and perseverance.