Happy birthday
Hopefully the hurting is mental and not physical.
I get down on my birthday, also in Sept, but shake it off. It's just another day after all.
One thing that's fun is to think back roughly 9 months and wonder what brought you here. Was it a holiday tryst between the parents...maybe a way to stay warm...pure and simple boredom...Who knows...but take solace in knowing that at some point you kicked ass for a brief moment and beat millions of other assholes in the race for your life.
Today you celebrate being the ultimate swim champ.
Then think about mom and dads "o" face

and cringe awkwardly and laugh.
Now get your ass out of bed, have some pancakes, maybe crank one off, then go have an adventure.