I don't really run during the fasting month.
I would work the whole day, rush back home to break my fast, and
then spend the next 2.5 hours in the mosque. And believe me, those
nightly prayers can be quite a bit of a workout.
On weekends, I go for short jogs after 6 pm. I don't push
myself, and I stop when I'm overheated.
Hopefully won't lose too much of my current fitness. Luckily AHM
this year is three weeks after Hari Raya - that is three weeks for
me to rebuild my fitness. In previous years AHM was the first
weekend right after Hari Raya.