Turned A Sunday Stroll Into A Sunday Run

I headed out Sunday afternoon for what I thought was going to be just a easy Sunday stroll as a few sprinkles moved in.  Instead about a quarter of a mile into it, with some great tunes, I decided to turn it into a run.  Nothing too crazy - just covered about 3 miles total.  But woke up this morning with my lower back telling me it wished I'd worn my running shoes instead of a pair that's already passed their running prime.  Time for new shoes!