There are several things one can do in their 20s to avoid regrets in their 30s and 40s. Here are some suggestions:

Invest in your education and career: Focus on getting a good education and building your career in your 20s. This will set you up for success and provide stability in your future.

Build a strong support system: Surround yourself with positive and supportive people who encourage and challenge you to be your best self.

Take care of your health: Make healthy lifestyle choices, such as exercising regularly, eating a balanced diet, and getting enough sleep. These habits will help you maintain good health in the long term.

Travel and experience new things: Traveling and trying new things can broaden your perspective, teach you new skills, and create lasting memories.

Save and invest wisely: Start saving and investing early to secure your financial future. Set financial goals and create a budget to help you achieve them.

Focus on personal growth: Take time to reflect on your values, beliefs, and goals. Work on personal development, such as improving communication skills, managing emotions, and building resilience.

Build strong relationships: Invest time in building and maintaining meaningful relationships with family, friends, and partners.

By following these suggestions, you can build a strong foundation for a fulfilling and regret-free future.