Guide your thoughts gently. Don't try to FORCE yourself to change all of your thought habits overnight. That's way too hard. Instead, start paying closer attention to the things you are focusing on at any given time.

When you notice that your thoughts are veering down a dark path, gently guide them back to a lighter path. Notice something good about where you are right now and focus on that. Think about something that makes you smile. Recall a few funny jokes.

Within minutes, it's possible to shift your thoughts dramatically toward the positive, but make sure you do it gently, softly. No big, jarring movements, vibrationally speaking. ;-)