maybe try some weight lifting, push ups, etc
You have to do quite a lot of hard exercise for your body to recover from a dry fast.
The 1 day dry=3 day water doesnt really stack up, it is much better/harder on the body than that imo, depends how much water you drink of course.
I ended a 3day 17hour dry fast on Saturday, did some gentle push ups a few hours later and started to get my strength back.