Life is too short to dwell on the negative things. Since there is never a shortage of negative people and comments, you need to put your efforts in the positive!
If you have an idea that you think can help you to be successful, go for it! Many people will tell you that you are crazy for taking a risk. Well, nothing ventured nothing gained. I can understand why people might be like that, since they are afraid of the unknown.
Most of the people who have doubts are usually unhappy about their situation. They aren't willing to take the appropriate actions to better themselves, so they aren't in favor of what you want to do.
We all make mistakes but we also get it right, eventually. When you find something that is working, exploit it. Milk it for all it's worth. Once that is no longer working, move on to something else.
Having a positive attitude is key. When you are positive, you are confident. When you are confident, it shows. Your confidence will draw more people to you and what you are trying to do. Focusing on your positive over your competitors negatives, will work much better.
When we are given an opportunity to acquire an account and am asked about companies X,Y & Z, I never say a bad word about them. I only focus on why our company is the best choice for cleaning their carpets. Talking bad about someone only makes you look bad!
No matter what, stay positive!