Below, David talks about motivation. Excerpted from Episode #26 of the 37signals Podcast (listen or read the transcript).

I have a very hard to impossible time forcing myself to do things that I don’t want to do.

When I feel that lack of motivation, there’s always a reason. I instinctually know whatever I’m working on is not actually worth it — that all this effort I’m about to put in is not going to pay off. Or maybe I’m just not good at what I’m trying to do. Either way, it feels like a waste of time.

Plus, I find it hard to have a wide array of things that I’m interested in at the same time. I usually pick one thing and I get really interested in solving that. Any other task that doesn’t fall under that banner has a hard time capturing my imagination and getting done. I just put that on the back burner until whatever I’m naturally interested in gets completed or my motivation runs out.

When you have a natural interest in something, your productivity goes through the roof. Even though whatever I’m naturally interested in might not, from an objective point of view, be the most important thing to work on at that time, it is the most important thing to work on because of the productivity gains I get out of just being super fired-up about it. I have to get that out of my system. And I wind up doing things really quickly.

When you’re not working on something you’re inspired by, your efficiency is so much lower. You find more moments in the day to let yourself be distracted by email or reading on the Web or something else. That’s usually the key smell I detect when I’m working on something I don’t really want to be working on: I check email much more frequently and I engage in chats about things that aren’t related to what I should be working on.

On the flip side, when I’m working on something I’m really fired up about, I couldn’t care less about new posts on Twitter or whatever. Instead, I get whatever I’m working on done right away.