Is it a job?

When you go to work, is it easy to fall into and discover half (or all) of your day gone? If not, are there times that happens? 

When I get to work and start solving a problem, and follow up with building it, I find myself hours later not realizing its time to go home.  Other times I come in and dread doing some of the work, for me as long as the times I am doing what I love happen more than the not, I consider that a win, and sometimes wonder if it is even a job I'm at. Is it just some one who wants to pay me to keep doing my hobby?  Many people say that of you make your hobby your job then it won't be fun anymore. I guess my question is this, does your hobby excite you? Do you find passion in it? I personally would be surprised to find out you are.

Then again I have an addictive personality (why I stay away from bad stuff :)), when I like something I'll keep doing it until I'm forced to stop, I love building things and engineering things, and unless someone makes me stop I'll probably just keep on trucking.

What do you love doing, could you make that a living? I think there are all kinds of possibilities out there. Don't think you can find a way to make it work? Ask me, maybe I'll have an idea!