New here - My 'famous last words' moment

Evening all, new face around here. Figured I'd kick things off with a classic blunder. My biggest, and most expensive, lesson came from sizing. I had a decent run on $EURUSD, felt like I had the market's number, you know the drill. Decided to "press the advantage" on a pullback, thinking I could get an even better entry. Went in with a size that, in hindsight, was less an advantage and more a full-blown prayer to the market gods. Needless to say, the pullback kept pulling, my stop was a polite suggestion, and my margin account developed a rather unsightly bulge in the wrong direction. The market, as it always does, humbled me quite thoroughly. The only consolation? I learned exactly how much I don't know.