Personally, I think discovering a mission of service, or purpose that serves the greater good, is a useful guide to living a meaningful life.
It serves as a benchmark for the contributions one is making to humanity. For instance, is your work aligned with your purpose? If not, what work that’s also capable of meeting your financial needs will? As you reflect on that question with true interest and curiosity, answers will tend to appear.
Purpose guides your actions. “Who/how can I serve today?” is a useful question that adds meaning and fulfillment to life, particularly when the thought is followed with action. Just asking the question tends to reveal opportunities.
And insofar as heart’s desires – rarely will these conflict with what one knows as their purpose, in my experience. In fact, pursuing/fulfilling your heart’s desires often puts you in a place where you’re better positioned to give your gifts.
Discovering your purpose can result from desire and intention, followed by meditation, visualizations, or a full-fledged Vision Quest.
Just one man’s opinion.