What should I do if I'm a liar?
Why do you think you are a liar?
I try not to lie, but I always seem to continue telling lies.
It's good that you see that telling lies is wrong and that you need to change that behavior. Lying can be very hurtful to others and you need to find ways to modify this behavior. Speaking with someone could help you make changes in your behavior.
I don't know what to do now because no one will believe me.
It's great that you have acknowledged your tendency to lie. Since you are aware of the problem, you can take the steps to correct the behavior and try telling the truth.