Take a couple of weeks off, as if it were your work vacation days, but then line up a solid schedule of activities. Commit to going somewhere and doing something concrete a few days a week, such as volunteer work. It will be less of a transition if you HAVE to get up some mornings for a real purpose. In the remaining time, schedule in some "leisure" activities, like fitness, social visits, specific things to do with family, community events etc. Treat it like a job at first, because it's hard to go from having to follow someone else's agenda most of the time to just doing whatever comes up most of the time. That's a recipe for quick loss of direction and motivation. Eventually, you'll find a rhythm that works for you, but more structure at first is probably better than less/no structure.
As for an overarching philosophy, I've always found the questions "What you you value more than your own comfort?" and "What would you willingly get up at 3AM to do?" helpful. They're related questions, as they get you to think about what is so important to you that you're willing to endure inconvenience and discomfort in order to do. For me, that answer is "help animals." So my time and money is spent on supporting animal causes/charities, taking in strays, pet sitting etc. I'm an introvert too, but at least some of my time and effort needs to be other-focused or I feel like I'm not doing anything worthwhile. It doesn't have to be paid to be worthwhile, just of value to society. That's the way I look at it. Once you've answered these questions for yourself, then you'll know what to put on your "schedule."
