This is a wide world. There are many thousands of possibilities to take advantage of, and many more paths to take. The question is, which one to take? What do I choose? What do I really want to devote my attention, time and energy to?
Recently, I've been turning to the past for my own answers to this.
What are the things I loved as a child? What are the ideas that keep coming back, no matter how many years since I first thought of them? What are the brainstorms I had way back when that stayed with me?
For instance, the idea of the monsters. Painting my little monsters that were inspired by my kids and selling or showing them in some way. Maybe even (some day, not now,) creating a children's book with them. That's an idea that burbled away in my brain for a while, exploded onto the scene in a burst of inspiration, and then swam away again, due to the demands of living life.
Or there's the image of a house, seen from the inside out. I first started drawing cross sections of houses when I was in first or second grade. Inside was furniture, and the inhabitants, going on about their lives. This idea morphed into the desire to be an architect, until I learned how much math it would take. The idea went away for a while until I was much older, then it showed up in my paintings again, in the form of buildings with scaffoldings, or buildings being built out of steel girders, both above and below ground. They were buildings both inside and out. From then on, I have been fascinated by the evocative image of the way the city is built, the houses and apartments fitting together in grids, and the lives burning away inside of those grids. The histories and stories collaged together to create something so very complicated.
Then again, certain ideas have come back again and again. My first attempt at novel writing was in the Science Fiction/Fantasy genre, and that has come back after years of not writing or of trying to write serious literary fiction. My space ships and colony planets are back, along with the relationship of sisters, the power and mystery of the wilderness, and rebellion against oppression.
These ideas, images and questions have come into and gone back out of my life so many times. But they have never gone away.
It is those things that don't go away that have the staying power to feed your passion. It is the dreams that keep poking at you that are the ones from the bottom of your psyche.
How to capture them?
Never throw anything away. Have envelopes to toss them into, or an old trunk or whatever, even if you think you will never look at them again because they are complete trash, DON'T throw them out. Some day, a few weeks from now or a few years, you might go through that pile of discards and discover it wasn't your passion that was lacking, it was your fear and insecurity that was taking over. If you look at that old idea, and the spark comes back and it starts living in you again... hold onto it. (Let us ignore for now the urge to organize and purge and get rid of clutter. For the ideas, don't let them go.)
Another way to track these old passions is to keep a journal and every once in a while go through the old entries and take note of those things that keep coming back, those wishes and hopes and ideas and projects.
If you don't have a backlog of papers and books documenting your old ideas, then time to delve into your biggest storage closet... your memory. Think back to your favorite activities as a child and take them up again. Write about something you loved to do when you were a teenager or young adult and talk about what it was that got you, your feelings and thoughts while you were engaged in the activity. Or talk with a good friend about the dreams you always had, whether those were sleeping dreams or waking ones. Share your dreams and pay attention to those things that keep coming up.
Here's something that you shouldn't worry about: why those dreams went away. Sometimes we aren't ready to go after them. Sometimes they need more time in your subconscious, or you need more time in the world before the seed of the idea can bloom into life.
The important thing is to find those passions that won't go away, no matter how busy you are or what you have to do to pay the rent or where your actual life has taken you. If they keep coming back, if they won't go away, those are your passions-- those are the contents of your soul. Pay attention to them.
What are the ideas and dreams from your past that keep coming back? Can you imagine taking them up again?