Great post by Maciej Ceglowski on the fifth anniversary of Pinboard. I particularly liked this part:
I find that the longer I run the site, the more resistant I become to the idea of ever giving it up, even if I need to take the occasional break. It is pleasant to work on something that people draw benefit from. It is especially pleasant to work on something lasting.
I feel the same way about Shoots & Leaves. The feedback I get telling me how people use it is a huge motivator.