What are some techniques or things you can tell yourself to pick yourselves up after a failed/awkward social interaction or afc-like behavior?

I recently had an assignment for uni that required me to go to a study lab in a certain building on campus and talk to the staff on duty there for just a few minutes. I arrived at 4pm, walked in the room, it was dead silent. There were two guys working at computer terminals; one of them had to be the staff on duty. At this moment I just froze up and went total AFC; instead of simply going for what I wanted ("Hey guys, I'm here to do the xx assignment") I simply sat down at a computer terminal with the excuse being that I wanted to look up the guy's name first before approaching any of them. I ended up on that computer for nearly 45 minutes reading about Scott Pilgrim vs the World (great movie, by the way) while TWO other people came in and got their assignment done. Finally I just manned up and did it but honestly I'm so embarrassed and angry at myself for wasting that time and failing to complete this basic expression of self sufficiency and dominance. There weren't even any women involved.

It seems unhealthy to dwell on things like this (negativity can never be good...right?) but at the same time just sweeping it under the rug and saying "better next time" doesn't seem like it would help very much either. What do you guys think?