I hadn't thought about the apps but the surfing and skating for sure!  Aside from physically looking young you're just young at heart!  It's funny cause a few years back I bought a street long board to get back into skating myself but quickly realized it was the wrong board to start back with!  I'm no spring chicken but could still get on it and go.  It was a lot of fun while it lasted though but way to fast of a board having dull skills at the time.  I'm gonna pass it along to my son soon.  I think he'll enjoy it.  Words my grand father told me that stuck when he was in his eighties were " you're as old as you feel and I feel 15!"  Now, I don't feel 15 mentally or physically but I certainly don't feel like I'm in my mid 40's either and you my friend absolutely don't resemble your age from what I've learned of you.  My hats off to you!  Livin' the dream.  Enjoyed!