Throw yourself into new environments. Truly, the only way you'll see change in yourself is if you add something new into your life. To do this, you'll need to pick up new behaviors, new people, and new activities. You can't do the same things over and over and expect different results.
Start out small. Join a club. Get a job outside your skill set. Start reading up on the subject. What's more, keep yourself out of old environments. You don't want to hang out with people who do the opposite of whatever it is you're trying to achieve.
Condition yourself. If you're afraid of spiders, put yourself in a room with one. Day by day, inch closer to it. Eventually, you'll be sitting next to it. Even later, you'll be holding it. Constant exposure dulls the brain from feeling fear. Now take "spiders" and replace it with whatever your goal may be.