Allowing negative thoughts to grow within your mind influences your reaction to situations, producing negative results. Consciously make an effort to replace these with healthy thoughts. Accept the fact that everyone occasionally fails, but see it as an opportunity to learn from the experience so you can do better next time. To overcome negative thoughts jump to Thinking more positively. Think optimistically. You can change your thoughts into healthy, productive ones. It will require effort and and persistence but you're capably of both, right? It's also important to understand that you, and you alone, are in control of the thoughts that pass through your mind.