I love building things, mostly large projects at companies nowadays. The current one: hooking up all machinery in a factory to the network, automating a lot of stuff and giving all departments the tools and reports they want.
The challenge isn't technical most of the time (to me), but in making it all happen. Coming up with the things they want, getting enough supporters and a budget, and implementing it they way I think it should be done. And I'm an (expensive) hired worker, so if it loses momentum, I'm out.
I like that.