Dragon Ball Super opened with the reveal that Gohan gave up martial arts and quit training in order to focus on academics and raise his family following the end of the 
Majin Buu saga in 
Dragon Ball Z. As a result, his power level has dropped dramatically from when a Mystic-powered Gohan manhandled "
Super Buu." This was more than evident when Gohan was easily manhandled by Beerus during the 
Battle of Gods arc and Frieza's henchman in the 
Resurrection of F arc.
However, a visit and long chat with 
Future Trunks during the most recent 
Dragon Ball Super arc will apparently serve as motivation to get Gohan back in the fighting game just in time for the next arc, which is titled the 
Universe Survival saga.
For more information and a detailed breakdown that will get you up to speed with 
Super, 
head over to our sister site, AnimeMojo.com.