History often prevents us from doing great things together.

Here comes Sofia, for example, taking her seat at your weekly managers' meeting. You know she's good at what she does, but that massive screw-up she was responsible for three months ago --with your best customer, no less -- still stings. You'll complete the meeting politely, of course, and she will have no idea you're still harboring hurt. But you'll also fail to collaborate at the level you could-- and should.

Now here's Fred sauntering through the conference room door. You know he's absolutely the best guy for that exciting new project you have, but you find it hard to engage with him at present, because you know he's in open conflict with another manager and with you for taking the other manager's side. To prevent any further grief, you'll give the project to someone else and it won't be as well executed as it would have been if Fred had managed it.

And now you're half way through the managers' meeting, but only one-tenth of the way through the agenda. Why? Because you, and Sofia, and Fred, and Mateo, and Kirsty-- in fact everyone around the table -- has at least one issue with someone else. They all nurse some grievance, some story, some narrative, some perspective that colors and warps your interaction as a team.

No-one's being mean. No-one's being ornery. Heck, except occasionally for Fred, no-one's even impolite. But the little asides, the passive-aggressive comments, the only-just-concealed eye-rolling is slowing everything down. Having to steer every meeting as if treading through a minefield of hidden emotions is draining the lifeblood of vision, innovation, creativity and passion from your interaction as a team. It's making you mediocre at best, and, you fear, increasingly ineffective.

What to do?

Simple. Declare an amnesty.

At least once a year have one meeting devoted to nothing but filling a couple of flip-chart sheets with every nursed grievance, every contested narrative, every 'he-said, she-said' and every "I can't believe you did that..." that the team can come up with. Then have each team member sign at the bottom that they absolutely, irrevocably agree to forgive and forget each and every point on the sheets.

Draw a line through each item-- a literal, black-Sharpie line, hug a little, and get back to being extraordinary.

Yes, you'll start piling up some new narratives, but at least they're new ones, right? And you can forgive those in six month's time.

If you have the intestinal fortitude for it, here's how to declare group amnesty in under 30 minutes:

1. Get everyone in a room together with a whiteboard or flip chart and a bunch of post-its.

2. Have everyone in the group take 10 minutes or so to write on a post-it the source of any major frustration they have with either the team as a whole, or with individual members, using one post-it for each topic, if they have more than one (most will).

3. After the time is up (or everyone has stopped writing), have the team members stick their post-its on the whiteboard or flip chart, and send them off for a 10-minute break.

4. During the break, 'clump' the post-its (put together all the post-its that cover the same topic or event) and from them produce a master list of every event, decision, statement, attitude or act that the team members have indicated is getting in the way of high-quality interaction.

5. Here's the tricky bit: When the group returns, go through the list, not inviting any further debate, but asking the group if they are prepared to declare a team 'amnesty' on those items – to draw a line under them, to let their annoyance, resentment or frustration go, and to agree not to let those issues cloud their interactions in the future. As you get their consent, draw a thick black line through each item.

6. Have everyone sign the master list indicating their agreement to amnesty.

This is team effectiveness 202 ‚ it's not beginner's stuff, and it's not for the faint-hearted. You need a strong facilitator and a mature team to pull it off. But if you can make it work, you'll see a turbo-boost in your team's effectiveness immediately.

Download a free chapter from the author's book, "The Synergist: How to Lead Your Team to Predictable Success" which provides a comprehensive model for building a cohesive, highly functioning team.