R, my flatmate in Aachen, Germany, told me what his coach told him: You should aim for running 70-90 min, then it really benefits your muscles. I thought: Hmm, I managed to run this long in the past, but I did it only a few times, very irregularly. So I decided to go for it again. This is the result. It felt really good to finally run this long again (and to take a warm shower afterwards :P).
I also found pleasure in running two-way trails, choosing a path I like for 35 min and running back the same path afterwards (2*35 min = 70 min). It is also easily extendable to 80 or at some point even 90 min by adding bits at the end of the path before running back.
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