Do you feel that maybe there's too much to do, and that overwhelms you, causing that anxiety?
I can spend hours on a computer obsessing over something, but can't get motivated because I have to go up stairs, turn on my monitor, open up browsers/programs/files, think about all the stuff I should do, that its just easier to put it off, because its not like I'm being paid for it or anything. People may rely on my hobby as a reference, but they aren't dependant on me.
I will try to leave my work open and ready to continue, hoping that I can by pass all these steps and avoid that anxiety. I just happen to be chilling in my office, my work just happens to still be open, THAT becomes my distraction, and it's easy to continue where I left off. Problem is, this rarely is the case because I had to restart my computer for some reason, or someone did it for me. But perhaps this isn't a problem for you. Whatever your work is, can you leave it spread out as a reminder and possible task remover?
Another thing that may help is to surround yourself with your obsession. If your hobby is your income you have a reason to be proud of that, so reminding yourself of the end result of your work may motivate you to continue. In my office I have various merchandise that represents both my work and my hobby, each one an achievement IMO. ...although I still have problems with motivation, so it's not like I can say that this helps