Too much was familiar to me a couple of years ago. Glad it is not so anymore.
http://jacquesmattheij.com/Are+you+suffering+from+burn-out
http://jacquesmattheij.com/dealing+with+burn+out
There are various useful discussions in the HN archives, including this one:
http://news.ycombinator.com/item?id=2300244
mrcharles's comment rings in my head to this day: "The first thing I've learned is that I can't accurately judge my limits."
Too much was familiar to me a couple of years ago. Glad it is not so anymore.