If all you do is level up all the time, yeah you're going to get burned out. There are other things to do in the game. Quests, missions, crafts, etc. They're not that hard to figure out and organize. I see a lot of fresh players these days go from East Sarutabaruta to G5 in about two or three months now, which strikes me as a depressing, torturous (not to mention questionable) grind. Unless you're an old pro who knows all the ins and outs and can afford all the equipment required, you really shouldn't be moving that fast. It's not a race to 75. Being level 75 isn't even impressive anymore.
Later levels can seem like a grind since the days of getting a level or more in one session are over, but you still don't have to meet the XP requirements the game used to have and there are old timers who hate you for it. You still level faster and lead a more charmed life than a lot of jobs, including my beloved BST. Then again, as slow as it is, the BST is probably having more fun. Successfully leveling BST can give you a stronger sense of accomplishment than killing any god can. That said, it's certainly not for everyone.
