How often can one start over?

I don't often quote Shlomo Carlebach; I'm not, I have to admit, a huge fan. In general, I am instantly suspicious of people who are that adulated.
Nevertheless, I am in the midst of job transitioning again - every few years, I reconsider what my original intention in becoming a rabbi was, and try to move myself into that track. For various reasons, I haven't been able to commit myself to that kind of work professionally (although I do a LOT of it for free), but I really someday hope to be able to do so, and so every few years, I look around myself and say what am I doing here?

At the same time, though, I have to think: is this really what I ought to do? Shouldn't I pick something and stick to it, even if it isn't exactly what I was aiming to do? Is "liking" enough, or does one have to be "in love" (especially in this economy)?

So, although, I don't think I can take this as any kind of final answer, I recently stumbled across this story, which I am taking as encouragement to try again - and even if I don't get it this time, maybe try again later - until I do:

Apparently Rabbi Shlomo was notorious for always being late, pretty much all the time. One time he arrived at a wedding at which he was to officiate, as usual, quite late. The father of the groom was extremely upset, and only got more so, as the rabbi worked his way around the room greeting people and talking to them. Finally the grooms' father stomped up to him and angrily yelled, "DO you realise that you're late? Rabbi, you're late!"
But Rabbi Carlebach merely handed his guitar to someone standing nearby, seized the groom's father with both hands and yelled back, "It's never too late! Never!"
For a long while, the groom's father merely stood there, silently crying.