It's hard to be sure you've made the right decision. But it's vital not to question a decision once it's made.

The other day I was standing in my field, a spiraling plastic strip in my hand. The strip would protect a young apple tree from being chewed by mice over the winter and I was wondering whether my tree was too big to need it anymore. Then I laughed at myself. I'd already carried the strip all the way from the garage to the apple tree which was most of the effort involved in this job. It was an old bad habit: choosing a course of action, then stopping to question myself halfway through.

That may be fine when it comes to garden dilemmas, but it's fatal for a manager or entrepreneur when the stakes are a lot higher. I've worked hard over the years to kill my habit of second-guessing myself, at least in my professional life. I'll admit it: I'm still far from perfect. But it helps to remind myself of these four truths:

1. You can never know everything.

Face it: You will never have all the information you need to make a good decision. But you have to make it anyway, so do your due diligence, listen to your instincts, and go for it.

The good news is that if you're working in the face of unknowns, so is everyone else, including your competitors.

2. Few decisions are irreversible.

If you make this decision are you stuck with the consequences forever? The answer is almost certainly no--even a tattoo is removable. Some believe there really are no wrong decisions because each one gives you the opportunity to learn, and to adjust for the future.

So commit to giving your decision six months or a year to truly test it out and know that if it turns out wrong, you can make a different decision later.

3. Few decisions are catastrophic.

Years ago, my colleagues and I made a disastrous hire for a key position. The woman in question seemed great and came with good credentials and glowing recommendations, but she botched key tasks, drove valued personnel to resign, and wasted tens of thousands of dollars before we learned of our error and replaced her. It was about the worst mistake we could have made and it rattled our faith in ourselves, but it didn't rattle our organization as badly as I'd expected. A few months later we had hired a replacement and were back on track.

So stop fearing that one bad decision will bring everything crashing down. Your company is more resilient than you think and so are you.

4. Indecisive is worse than wrong. 

This has been a difficult lesson for me to learn, but it's an important one. The people who work for you can forgive you for making a mistake, even a very bad one. It's much harder for them to forgive wishy-washiness or paralysis. The reason is simple: By definition a leader needs to be followed. And it's tough to follow someone who doesn't seem to know where to go.