Wow. Yeah, I identify with this guy's description a lot. Except for the athletics--I was born with messed-up knees and that kind of stunted the athletic area of my ISTP-ness. I've done weight lifting and horseback riding instead, but I find that I'm more competitive against myself than against others anyway.
My IxTJ father's in ministry and I've always been very involved in the church; I also have an active interest in business and economics--more so than math/sciences.