I'm a 32-year-old hobby jogger with intermittent periods of semi-intense training under my belt. I'm coming back from a few months of casual running and want to ramp my mileage up from 20 to 40+ mpw. No specific goals except getting fit and not embarrassing myself in local races.
Over the past few weeks I've started to mix in longer runs, e.g. ~50 mins on hilly trails, and some intensity, e.g. fartleks once per week. But my legs feel trashed all the time and most of my runs are a struggle.
Is this just a function of getting in shape? Or are there specific things I can do to recover more quickly?