Your 20s are a time to make mistakes, learn from them, and mess up all over again.

However, by the time your 30th birthday rolls around, there are are some key things you should know.

Dr. Isaiah Hankel, entrepreneur and author of “Black Hole Focus: How Intelligent People Can Create a Powerful Purpose for Their Lives,” shared the 10 of them in a recent LinkedIn post.

Here are four of our favorites:

1. You’re not the only one with the good ideas. “Everyone has good ideas,” writes Hankel. “Most people know this. The problem is that most people see their ideas as being in competition with other people’s ideas.” Our competitive nature prevents us from recognizing that other people’s ideas ultimately help our ideas. “Start listening to what other people have to say too,” he advises. “Be willing to explore their ideas. Not just your own.”

2. Friends are worth more than money. “It’s better to have 100 friends than 100 dollars,” writes Hankel. “It’s easy to think that money is the answer to your problems. It’s not. People are the answer.” Your network and the relationships you develop are invaluable — things that cannot be taken away by a bank. “You need people to accomplish big goals. Your network is your net worth.”

3. A little bit goes a long way. “Everyone overestimates what they can do in a short amount of time but underestimates what they can do in a long amount of time,” says Hankel. “Breakthroughs don’t happen in one explosive moment. They happen over time. By small, repeated efforts.” Start small and do a little bit every day — the end result will surprise you.

4. Control what you can control. “You can always control how you handle a situation,” writes Hankel. “Bad things happen for no reason. Life is not what happens to you, it’s how you handle what happens to you.” The intangibles are inevitable; rather than fretting over the why, focus on what you can always control — your attitude and your attention. “No matter what’s going on around you, choose to focus on solutions, not problems. Focus on what you can fix, change, leverage, spin, and learn from. Don’t focus on the unfixable. Let it go. Move on.”

[Business Insider]