When I was a commercial loan officer for a large bank, my boss taught us that you should never make a loan to someone who is following his passion. For example, you don’t want to give money to a sports enthusiast who is starting a sports store to pursue his passion for all things sporty. That guy is a bad bet, passion and all. He’s in business for the wrong reason.

My boss, who had been a commercial lender for over 30 years, said that the best loan customer is someone who has no passion whatsoever, just a desire to work hard at something that looks good on a spreadsheet. Maybe the loan customer wants to start a dry-cleaning store or invest in a fast-food franchise—boring stuff. That’s the person you bet on. You want the grinder, not the guy who loves his job.

For most people, it’s easy to be passionate about things that are working out, and that distorts our impression of the importance of passion. I’ve been involved in several dozen business ventures over the course of my life, and each one made me excited at the start. You might even call it passion.

The ones that didn’t work out—and that would be most of them—slowly drained my passion as they failed. The few that worked became more exciting as they succeeded. For example, when I invested in a restaurant with an operating partner, my passion was sky high. And on day one, when there was a line of customers down the block, I was even more passionate. In later years, as the business got pummeled, my passion evolved into frustration and annoyance.