I don't really like any type of "computer repair"...we really focus on business, not residential. Troubleshooting weird computer issues is a time sink...and something you don't really get to charge for every minute.
My favorite line of "IT Work".....is implementing new/bigger things for clients.
One example, already mentioned by someone early on in this thread...taking a business with a little peer to peer network..and upgrading it to a good server based network. Like moving a business from residential pop/imap e-mail, to proper business grade e-mail, in the old days, with Small Business Server. Lately, Office 365, and an Essentials server or server with Essentials Role. Showing them the cool things they can do with a good business grade e-mail system, like public folders, distribution groups, external contacts, aliases, etc. And the other perks..letting them remote in via the Remote portal. Or outside file sync with DattoDrive.
Introducing a nice new server cabinet with rack mounts...upgrading servers, virtualizing servers...love those!
But lately I'm trying to focus on wireless networks, including outside...like marinas, campgrounds, and long distance shots like the 6 mile one over water I did last year.