again, faster

I think i have ended every metcon workout saying to myself, "I should have done that faster," or, "I should have taken less/fewer breaks." Yesterday was no exception.
5 rounds for time of
50 foot lunge with 45 lbs overhead
21 burpees
15:20
I know I should always be pushing, but on this one I was a little disappointed. I felt a little 'less' going into it, but I pushed anyway. I went into it looking for a sub 20, but when I realized how things were going, I started shooting for sub 14. When I was done, I realized that I don't push hard enough through the lactic burn. Most times, as I walk away, I want to turn around and try again for a better time. Hopefully that is only competitiveness and not obsession. Either way, I still think, "again, faster."