Honesty comes in many versions: first is honesty with ourselves. Is it the genuine article that people see, or is our image coming through mirrors and smoke? I found that every time I fool myself and try to be something that I really am not, I feel insecure. I love how an old song says it: "Always be a first-class version of yourself, rather than someone else's second-class version."
Then there is the honesty in our actions. Are you honest at school, with your parents, and with your boss? If you were dishonest in the past, and I think we all were, try to be honest now, and notice how it makes you feel good. Remember that you cannot do things wrong and feel good. This anecdote from my friend Luis is a good example:

In my freshman year of college, there were three guys in Geometry class who weren't doing well in math. I was very good at the subject. He charged them a certain amount of money for each exam he helped them pass. The tests were multiple choice, so I wrote down the correct answers and gave them to her.
At first I felt like I was making money, a kind of good job. I never thought about how it could harm us all. After a while I realized that I shouldn't continue, because I wasn't really helping them. They weren't learning, and over time they would only get worse. And certainly cheating wasn't helping me either.

Honestly, it takes courage to be honest when everyone else gets away with cheating on tests, lying to their parents, and stealing at work. Remember that every act of honesty is a deposit in your heart and will give you strength. As the saying goes: "My strength is like the strength of ten men, because my heart is pure." Honesty is always the best policy, even when this is not in style.