By this I mean not the opportunity to expand your own sense of mastery of the world, but the opportunity to expand your service to the world.
If you gain something external it can be taken away; all material things are transient. But the service you offer the world is eternally yours. Service gives you something long-lasting, both in the purpose and meaning it builds within you, and in the impact it has on others, which may even outlive you.
The opportunity to serve is the most valuable opportunity worth pursuing.
Live to give and give to live.