Some people mistake burnout for boredom.
You need to be able to look at whatever you do with a sense of freshness every time, otherwise you risk falling into the doldrums. If you can't do that step away, refresh yourself and your outlook, and remember what it is you are trying to accomplish and why you chose to do what you are doing in the first place.
If the problem persists, then quite possibly you are not in the correct field for your personality.
There has been tremendous change in adult just in the past few years, and the future promises even greater change.
Maybe it is just what you are doing that is not fulfilling, in which case you may need to reassess your goals and move in a different direction, either in or out of the adult biz.
ADG