This really is a very important point. The fact that James immersed himself in the world in all respects(day job and as an amateur) likely increased his chance

This really is a very important point. The fact that James immersed himself in the world in all respects(day job and as an amateur) likely increased his chance of success. If you were asked on the spot to name the names of a few acquaintances(not people you know, only people you know of), you'd probably name those who pepper your life most often. Now if those people made it known that they're fisherman or actors or really into painting or programming or etc. Then the next time someone asks "Hey you know of any good programmers? You know of anyone interested in painting? You know...etc"; you'll be able to say yeah I know a guy, he washes my car every other week. It works out for you(because you recommended a person) and it works out for the other person because they get a shot at doing something they love. James Garner allowed himself to seep into the consciousness of as many people as he could so they'd associated him with what he loved; smart move. A corollary may be that the more people that know what you love, the more you become a person who loves that thing; both personally(mentally associating yourself as an actor/writer/programmer/etc) and professionally("Yeah, James he's an actor. Ben wants to be a painter. Sheila is trying to be a cartoonist").