Make something people can use.
Put it in their hands.
See what happens.
If they’re eager to pay – attention, time, money – you’re onto something.
Watch them. Listen to them. Tweak it. Make more of it. See what they think.
If they tell their friends – and if their friends tell their friends – then you’ve got it.
What change do you seek in the world? Who are the people you seek to serve?
You’ve got it when they’ve got it.
You’ll know you’ve got it when you meet someone for the first time, and the thing you made is already in their hands.