As a software engineer near Venice FL in his early 20s there isn't a lot to do here still. I guess some people do enjoy going to the beach a lot but it definitely gets old.
Venice YMCA has a ton of offerings--rock wall, skate park, basketball gym, adult leagues, etc.
You have pretty much every other normal amenity, like theaters & community college.
Tampa isn't far for theme parks, concerts, etc.
You're missing having a hometown bar scene, but those aren't too far anyway (and the 20-somethings make do with what's available, anyway).
What do you feel like you're missing?