What are the most difficult and useful things people have to learn in their 20s? originally appeared on Quora - the knowledge sharing network where compelling questions are answered by people with unique insights.

Answer by Nelson Wang, entrepreneur, writer, and founder of ceolifestyle.io, on Quora:

Here are the top 20 things I learned in my twenties:

  1. Marry your ideas with execution. Ideas are good. An idea married to execution is better. So you came up with 100 good ideas. That's great. Can you actually make any of them a success?
  2. Being able to focus is a skill. When I was in my 20s, I wanted to be a writer, a producer, an actor, a financial analyst, a salesperson, and an entrepreneur. And that was just in the category of careers. Imagine what that list looked like for multitasking my daily activities. As I got older, I realized that our time and energy is incredibly limited each day. Being able to focus is absolutely critical if you want to make a big impact.
  3. Perseverance is the most important skill you can learn. You will fail, sometimes over and over again. It's human. No one's perfect. It's not about you fall, but how you get up each time. Did you learn? Did you quit when it made sense? Did you try again? Learn to persevere. I wanted to quit after writing my first book because it was such a flop. Guess what? I continued writing for years and eventually I got published in Forbes, Time, Fortune, Inc and Business Insider. #StayTheCourse.
  4. Working hard doesn't guarantee success, but it makes it more likely. Working hard does ensure a few things: you'll learn a lot, you'll develop discipline, and you'll typically see more opportunities. Combine working hard with working smart, and you've got a recipe for success.
  5. Work is very personal. You spend about 24% of your time at work your entire life. Bring your whole, authentic self every single day. (This is Sheryl Sandberg's idea). Do you think people say, "Gosh, I love working with Nelson because he's so robotic and shows no emotion or personality." Nope, didn't think so.
  6. You don't know everything; learn from others. According to Socrates, "The only true wisdom is in knowing you know nothing." Okay, I think Socrates is kind of right here. Just kind of. I think you know something. But none of us know everything. Leverage the intellectual power of your network and always be insanely curious to learn from others. You never know what incredible knowledge they can share with you. For example, the other day I sat down with a friend for a coffee and learned how he built a business that generated tens of thousands of dollars in sales in a few months with only a few hours of work a week. #MindBlown.
  7. An important part of business is setting proper expectations. Learn to let people know in advance what to expect when they work with you. This is half the battle.
  8. 15-minute meetings can be ultra productive. Hour-long meetings are almost always too long. Seriously, when's the last time you really had to have a meeting that long to be productive? Try aiming for 15 minutes. It forces you to be concise.
  9. You can lead, with or without a title. When I worked at a huge technology company in Silicon Valley, I was an individual contributor. I came up with an innovative idea for generating sales and new customers on my own and soon the word spread about its success. Before you knew it, I was asked by the executive leadership team to present it nationally to the entire team. That's when I realized, leaders lead by inspiring, coaching, and empowering people to be great. You can lead with or without the title.
  10. First impressions make a difference. I flew to over 70 cities in 2 years for business. When I wore a hoodie and fell asleep once, the stewardess woke me up and said, "It's time to wake up, teddy bear." I was 29 years old at the time. When I wore a suit (because I had business meetings that same day), people would treat me differently and call me "sir." First impressions make a difference.
  11. Time is the most valuable currency. In college I spent an inordinate amount of time playing Mario Kart and partying. Yes, it was fun, but as I've gotten older I realize now how valuable that time was. If I could go back in time, I would spend that time pushing myself to learn, to grow as a person, to spend more quality time with my friends and family, and to even start a business. Also, when I was in my early 20s, I often thought about how to make more money. Money is important. We need it for food, shelter, and clothing. It's absolutely necessary in life. But the most valuable currency is time. Time with our loved ones. Time to live a life we can be proud of. Time is finite. Spend it wisely.
  12. Most arguments don't matter. Choose your battles wisely. Most people have a limited amount of social currency.
  13. Sometimes only you can motivate yourself to be great. Sometimes one of your idols can inspire you. Sometimes a family member can get you amped up. Sometimes a love interest can drive you. And sometimes, only you can motivate yourself.
  14. Figure out your why. Your purpose will fuel your drive. This is the strongest motivator of all.
  15. Have strong opinions, weakly held. I love hearing people talk about their ideas and opinions in a passionate way. It shows they care. I also love it when people realize that there's a better way to do things (even when it's different from their own opinion). Be passionate and be open to changing if there's a better way.
  16. Data-driven decisions are powerful. "I think the "subscribe" button on the site should be blue," said the executive. "Why?" replied the marketing manager. "Because, I just think blue will do better." Instead of simply making decisions based on opinion, consider leveraging data to arrive at an answer. For example, an A/B test is a common and great way to find out which variations perform better on a webpage. Embrace testing.
  17. Intuition can be just as powerful. Sometimes, though, intuition can be really powerful. When Steve Jobs created the iPhone, he had an incredible sense of what he thought people would want. It reminds me of the quote from Henry Ford: "If I had asked people what they wanted, they would have said faster horses."
  18. Your most important investment is in your health. Treat your body well and it will thank you many years later. Eat more fruits and vegetables and exercise regularly. Your energy, focus, and general happiness will improve. My secret to how I got on track with my health? Eating a green smoothie daily for 30 days.
  19. Integrity is what you do when no one is looking. But no one will ever know, you think to yourself. Yes, but you always will. And you'll have to live with it. Do the right thing.
  20. Love is what really matters. At the end of the day, love is what matters. Love more.

This question originally appeared on Quora - the knowledge sharing network where compelling questions are answered by people with unique insights. You can follow Quora on Twitter, Facebook, and Google+. More questions: