Been happily beemindering new activities I want to do for a month or two now, and everything has been going fine. Recently I added one for working on my game (a side project from my full time job at this point) at least 6 hours a week, which sounded pretty reasonable to me. This was my first beeminder failure -- admittedly, I had a terrible week (grandfather died, flying to another city for the funeral and back, coming down with a bad case of flu the very next day), but it was also eminently avoidable if I'd done more work before the deadline started closing in.

My take away from this is I should start my beeminder goals off much less ambitiously, give myself a week or two to establish the habit with beeminder as a reminder & tracking system, then when I have a bit of backlog built up for unexpected problems start ramping up the road until I reach a goal level I'm able to maintain, and happy with.