Big question indeed!

Further to Debra’s response above, I find Jim Collin’s Hedgehog Concept in his book “Good to Great” helpful. The basic premise is that there are 3 areas to thing about/action:
1. What are you deeply passionate about?
2. What can you be the best at?
3. What drives your resource engine (does it generate revenue)

Here’s a blog about it that may help:

Have fun!