After I finished law school in my mid-20s, I went on to clerk for a federal district court judge. The demanding caseload and time commitment made for a particularly intimate working relationship with my colleagues. I earned very little money and logged countless hours that year, but I did it for the experience and to make my first connections in the legal field. But I made one critical mistake when I ended my clerkship: I didn’t maintain my relationship with the federal judge. Frankly, I was 26 and didn’t know any better. But I now realize she would have been a great resource for me years after I left her office. When I reflect back on that time in my life, I can clearly see where I took advantages of certain opportunities and where I failed to see opportunities that were right in front of me. If I had the chance to give my 20-year-old self career advice, I would tell her to make sure to focus on the following four things:

Work really, really hard
This sounds generic and obvious, but becoming an expert in your field or the go-to person in your organization will help you advance. Being irreplaceable in your business leads to a solid career trajectory, and can help ensure that when you’re in your late 30s and 40s and you want more of a work-life balance, you will be in a better position to do so. If you do the hard work early on in your career, you’re much more likely to earn the flexible opportunities you’ll need later in life.

See also: How Millennials Can Succeed at Their First Job

Take risks
Don’t be afraid to take on new responsibilities. Be the first one to raise your hand for an assignment. There will always be a safe way to do something; avoid the safe way. If what you’re doing doesn’t feel challenging, you’re not taking a big enough risk. And don’t worry about failure; it’s just another challenge.

Cultivate a network
If you meet someone professionally who strikes a chord with you, find a way to stay connected. That person could end up being part of your own personal board of advisors when you need career advice down the road. It might not be intuitive to hold on to people you meet at 25, but when you’re 35 or 40 you might really value the input from someone who knew you when you were just starting out. Don’t let yourself lose touch. I made that mistake with the judge despite knowing she was someone who made many of the same decisions I ultimately had to make in my career.

Ask questions
There appears to be a myth among young professionals: if they ask questions, it means they don’t know what they’re doing so they end up not asking. Don’t do this. Be comfortable asking questions. If I’m sitting with colleagues and someone starts talking about something unfamiliar, I have no problem saying “I’m sorry, I don’t know what we’re talking about” or, “I am out of my depth here, can you help me?” Asking questions is how you gain credibility.

Read all answers to the MPW Insider question: What should every 20-something do to set themselves up for success?

How to Overcome Challenges of a Career Change by Lisa Lambert, vice president of Intel Capital.

What every 20-something should know about their first job by Cathy Engelbert, CEO of Deloitte.