do whatever you enjoy. if FATEs are annoying you, switch over to Dungeons; if both irk you, you could even go explore maps (I get like 30+k exp for completing 1 set of map in late 40s); if none of these interest you at all, and you have no more quests to do, then maybe take a break and level another class/gather/craft or help out FC/LS mates with stuff.

No matter what you do, do it often enough it becomes a grind. However, the prospect of getting 50 (for a myriad of reasons - I am very motivated by the ability to don the full AF for example) usually provide sufficient drive for players to get over the "grind". That being said, if EVERYTHING in the game feels boring to you, then maybe this just isnt the right game for you and do not feel bad to face it and accept it