You can take your purpose seriously and still go to work tomorrow. Your salary can give an idea time to grow. You do not have to turn every beginning into a dramatic exit.
I use excitement and intuition as an inner guide. Then I want to test the idea in real life. A feeling can give you a starting point; it cannot promise you a career.
Choose something you enjoy doing enough to explore beyond the fantasy of success. Make a small version, practise a skill, or help one person with it. Notice which part holds your attention when there is effort involved.
A job can provide experience while you learn. The important question is whether you are leaving any room to discover what you care about, rather than postponing that question indefinitely.
After a period of practice, review what you actually did. What did you enjoy? What was useful to someone else? What would you willingly improve? Those answers are more concrete than waiting for a perfect description of your purpose.
You do not need a dramatic announcement to begin. Take the interest seriously enough to give it time and honest effort. The direction can become clearer through doing the work.