I get no do-overs when one of my forty-five minute lessons doesn't go as planned. I take what went well, look at what didn't and improve for next time. The only reason I got as "good" as I did at teaching was that I had over fifteen lessons a week to figure out what the heck I was doing the forty-five minute period structure was a harsh limitation, but one that I had to work with. Freelance translating and independent game development have no periods. If I get hung up on how to translate one line or how to make a game's control feel, that can dominate my body until I physically can work no logner. But then it consumes the mind until I must sleep. At that point, it can consume the soul.
With deadlines, self-imposed or no, on the horizon it becomes increasingly easier to forget that a nap, a shower, a cookie or even a glass of water can be all that stands between frustration and an answer.