>>thesz+o1
The saying isn't "The only way..." but "The best way...". Of course one may improve with all the things you mention, and it's a tongue-in-cheek statement anyway, but there's a grain of truth to it. I saw it quoted by one of the greatest teachers in golf, Harvey Penick.
>>paulmo+(OP)
Similarly, it's probably not a coincidence that the best F1 driver happens to be the one who started driving karts the earliest (4 years old) and spent the most time doing it out of even all those elite ones.