It's much harder to change others' perceptions of our behavior than it is to change our own behavior. People's perceptions of us are formed when they observe a sequence of actions that we make that resemble one another. When other people see the pattern, they start forming their perceptions of us.
For example, one day you're asked to make a presentation in a meeting. Speaking in public may be the greatest fear among adults, but in this instance you don't choke or crumble. You give a great presentation, magically emerging as someone who can stand up in front of people and be commanding, knowledgeable, and articulate. Everyone in attendance is impressed. They never knew this side of you. That said, this is not the moment when your reputation as a great public speaker jells into shape. But a seed has been sown in people's minds. If you repeat the performance another time, and another, and another, eventually their perception of you as an effective speaker will solidify.
Negative reputations form in the same unhurried, incremental way. Let's say you're a fresh-faced manager looking at your first big crisis at work. You can react with poise or panic, clarity or confusion, aggressiveness or passivity. It's your call. In this instance, you do not distinguish yourself as a leader. You fumble and your group takes the hit. Fortunately for you, this is not the moment when your negative reputation is formed. It's too soon to tell. But the seed has been sown--people are watching, waiting for a repeat performance. Only when you demonstrate your ineffectiveness in another crisis, and then another, will their perception of you, as someone who wilts at crunch time, take shape.
Because we don't keep track of our repeat behavior, but they do, we don't see the patterns that others see. These are the patterns that shape others' perceptions of us--and yet we're largely oblivious to them! And once their perceptions are set, it is very difficult to change them. That's because, according to the theory of cognitive dissonance, people see what they expect to see not what is there. So, even if you finally do choke a presentation - people will excuse it saying you just had a bad day or they will think it was great because that's what they expect. And, even if you save the day in a crisis, it will not change people's perceptions of you. They will consider it a one-off event or they will not notice your part in it at all.
So, what do you do? The challenge is that just as one event doesn't form people's positive perceptions of you, neither will one corrective gesture reform their views of you. Change doesn't happen overnight. You need a sequence of consistent, similar actions to begin the rebuilding process. This is doable, but it requires personal insight and, most of all, discipline. A lot of discipline.
You have to be consistent in how you present yourself--to the point where you don't mind being "guilty of repeating yourself". If you abandon the consistency, people will get confused and the perception you are trying to change will get muddied by conflicting evidence that you are just the same as you were.
Finally, you have to follow up with those whose perceptions you are trying to change. Go to them every month or two and ask, "Ms. Co-Worker, It's been one month [two months, three months] since I told you I was going to try to change this behavior. How am I doing?"
Your co-worker will pause and reflect, "You're doing good Co-Worker. Keep it up!" In this way, they will repeatedly acknowledge that they are seeing a change in your behavior. And, if you do fall back into an old behavior one time after a few months, they will remember how you have been doing great for such a period of time and will likely let it slide!