A significant majority of your anxiety and unhappiness likely stems from a subconscious disappointment in yourself for the great ideas and dreams that have been forever abandoned in your mind.
Although you will sometimes regret the things you carelessly say and do without thinking, you will never regret these things as much as the words and deeds you leave unspoken and undone.
Positive growth only occurs when you stretch yourself. What you think has to affect what you say and do. So say what you need to say and do what you need to do, starting now.