> FitnessAI is so simple your grandma can use it.

This is a terrible cliche. (More: https://geekfeminism.wikia.org/wiki/So_simple,_your_mother_c...)

How about something like:

* Your lifts should be hard, your tracking should be effortless. Record your set with a single tap and spend your rest recovering for the next (...or taking selfies, we don't judge).

This tells people exactly what the value is and tells the that the user that they deserve FitnessAI.