Something you’re just good at with minimal effort and/or you learned much more quickly than average.
For me, it’s paper snowflakes. My brain just seems to effortlessly figure out what cuts to make to the paper wedge to make it turn out exactly how I want it. Largely useless, but good fun and was a much-needed ego boost when I was a kid :]
Running. I’m pretty fit and I work out (retty much only bouldering tho). Despite running on average once a month I can run a 45 min 10k. I think if I actually trained for running I could be pretty good but I just prefer climbing as a sport.