Don't forget...the question mentions that this "transformation" is only for 30 days (1 month). It's also not really supposed to be a "time machine" where you go back in time to visit a time & place at a specific age...you're mostly thinking about if you could be ANY age for 30 days...what age would it be.
I think the idea is...if you could be ANY age (right now...today...this moment...May, 2019)...what age would that be? I think the question is focusing on...what age in your life so far has been the most fun...most rewarding...most satisfying...most physically fit...etc. Then you choose that age & live it again for 30 days.
Here's another way of looking at the question. Today is May 2nd, 2019. If you went to sleep tonight...and woke up tomorrow morning (May 3rd, 2019)...if you could wake up & be ANY age for 30 days...what age would that be?
- Nick
p.s. No Time Machines...at least not with this question.