It's not evil. Welcome to getting old... I can give you a list of exercises.
Or I could do the freeleticwhatevers.
Next two months will be a lot of running, probably starting this weekend. At least I won't be jumping snowbanks :(
I don't think freeletics is good for all-round body maintenance - too much repetition of a single exercise, and while it's mostly major muscle groups, in your case you need hip, glute, and hamstring strength, and freeletics doesn't really do any of those. Oh, and pec stretching, to stand you up a little straighter.
I can show you the exercises I'm doing before I run, will at least get you started on old-person-body-maintenance :).
Careful with ramping up the running. But you know that.
What is this "careful" you speak of?