30 years old

When you're young, it's easy to think you've got plenty of time to responsibly live your life and learn essential life skills. This is especially true in your 20s.

In your 20s, you're just out of school, working on advancing yourself career-wise, and you want to just enjoy your youth. While there's nothing wrong with that -- you should enjoy your youth -- you have to start some life planning as well.

By the time you get to 30, you'll realize you're too late to the party on things like getting your degree, living a financially healthy life, and, according to Redditors, dental care. Use your 20s to have fun, but make sure you also take advantage of being young. Sometimes, your youth is the exact right time to start good habits.

This is probably the philosophy behind Redditor give_me_wings101 question:

"What’s that one thing people in their 20s should definitely do before turning 30?"