2nd 10K complete

Negative splits are the way to go man.  If you normally run a 8:30 mile run a 9 minute mile for the first couple miles and then make up for the 9 minute mile by running a 8:00 - 8:15 on 3 and 4 when your body is warmed up.   Repeat and you'll stay around your target pace.

Regardless, congrats on your PR!   A 55 minute 10K is a great time!

Chad