Yeah, enthusiasm can add a layer of stupid to any of us. I can't count how many times I've tried to start a plane with the mixture at ICO. The last, and most memorable time, was in Reykjavik, getting a checkout in a rental C172. There was no checklist in the plane, and for a C172, I really should not need one!
When the check pilot put in the mixture to help with my third start attempt (and to save his battery), he asked me: "you are a pilot arn't you?". He was serious, I had only told him I was, I had not proven it yet. "Yes", I humbly said, "and with 6200 hours, you'd think I could start a C172 from memory!". Everything went fine after that...
Now, every time I fly, I assure a 10 second stop and sanity check, at least once before takeoff - I think I have done everything, but am I sure? Am I rushing too much? It's quite illuminating what I find I have missed!