Surprised by my own abilities!

I haven't been exercising reguarly besides from horseback riding since around february last year. Monday this week, I was feeling sort of uneasy and like I had too much energy. I decided to go for a run and bam, ran 6.2 km even though I haven't been running in almost a year! I was so happy and surprised! My time wasn't very good (48 mins) but that's not my focus atm, but apparently I'm not in as horrible shape as I though I was.

Ever experienced anything similar?