Many things can kill a career. Missing a big opportunity, getting passed over for a promotion, getting demoted or fired or losing a lot of money. You know the list.

It’s our worst nightmare come true; the screaming headlines and public humiliations that suck all the spirit and forward thrust from our professional lives, surrounding us with a negative don’t-come-near-me aura, as if we were walking hazmat zones.

But these humbling episodes are results, not causes. When people go from mojo — that spirit that begins on the inside and radiates to the outside — to nojo, it’s usually because of a series of simple, hard-to-spot mistakes that lead up to the humiliating result, like over committing.

There’s a saying, “If you want to get something done, ask a busy person.” It makes sense; a busy person is well-organized and not inclined to waste time or get distracted. But there’s a ?ne line between taking on a lot of work and too much.

It’s easy to see how people in corporate situations fall into this over commitment trap. If you’re good at what you do, everybody wants to rub up against you. They want you in their meetings, seek out your opinion or want you to run a project.

People with high mojo tend to be assaulted with opportunities. It’s how junior employees advance more rapidly than their peers; their enthusiasm and ambition tempt bosses to pile on the work until the employees cry uncle, which they don’t until it’s too late.

It’s even easier to see how self-employed people over commit. When you don’t have the cushion of a steady paycheck, every opportunity looks like your last payday. So, you say yes to everything.

I’m guilty of this. When I speak to groups, I show up, share what I know, and like any wage earner, get paid for my time. When someone invites me to talk to their organization, it’s a straightforward pay-for-work opportunity. If I show up, I get paid. If I say, “No, thanks,” I’m tossing money down the drain.

But then someone calls to hire me. I say I can’t do it. They persist. They flatter me, too, essentially saying, “We want you,” and they’ll take me on my terms. You have to be hard-hearted to say no to folks like that. Plus, the date will be several months away. Who knows what things will look like then? So, I switch from “Can’t make it” to “I’m there for you.” And I find myself unpacking in another hotel, preparing to get up on a nice Saturday morning to talk to a roomful of clients when I might be better served writing my next book.

I’m not whining — I know I’m describing a headache most people in my line of work would jump at. I’m also not saying the people who hire me under these circumstances get any less of my enthusiasm.

But the fact that I question my decision to accept the booking represents a threat to my mojo. It injects the potential for regret into the experience, and a tiny drop of that could bleed into my performance.

Still, you rarely hear people say, “I’m taking on too much work,” although most of us are working longer and harder than ever in today’s 24/7 economy. Perhaps they’re afraid of looking weak, as if they can’t handle any challenge that comes their way. Perhaps they can’t resist the call of being asked to help out; it’s a validation of their skill and another way of being told, “We love you.” Perhaps they really do believe they have superhuman qualities and that nothing is too much. Perhaps they realize “I took on too much” is not much of an excuse if and when they drop the ball.

Any of these reasons explains why over committing is one of the sweet but risky blowbacks from having mojo — and why it’s a stealth mojo killer.

Before replying with an enthusiastic yes to that next request, think of the impact on your mojo.

Are you doing what is right for the long-term or just saying what makes others happy in the short-term? Is what you are about to commit to going to increase the happiness and meaning you experience in life?