When I was in college, I wanted to work in the music industry as a booking agent or concert promoter.
"I like music," I reasoned. So I would love working in the music business, right?
The trouble with that reasoning was that my day to day wasn't spent listening to music or hanging out with bands. It was spent calling people on the phone, or creating marketing, or negotiating, or writing contracts.
"Scratch your own itch" is good advice, but not because of the motivation or energy it will provide. It merely grants you a ground floor understanding of the pain you're trying to solve. Because you are, presumably, among your target market.
As far as motivation is concerned, however, you would be better off focusing on a business with day to day tasks you love to perform.