As the adage goes, “a life without regrets is a life not lived,” but it is also “better to regret what you have done than what you haven’t.” The three biggest regrets of retired baby boomers center on the things they have not done and teach the next generation to make more informed choices.

1. Not Saving for Retirement Earlier

A rare absolute rule of finance is that people should start saving for retirement as early as possible, with the best time to start being in one’s twenties. Life expectancies are growing and show no signs of slowing down, so more money is needed to be stretched out for a longer period of time. Starting to save and invest as soon as one enters the full-time workforce can make a dramatic difference in the amount of money that accumulates by the time a person is ready to retire.

Many baby boomers failed to start saving on time and properly because they did not understand just how much money would be needed for their retirement. Some also did not know that receiving social security benefits or taking money out of retirement accounts before it is needed can have tax consequences that can substantially lower savings. Finally, many people tend to forget to adjust for inflation when considering whether they are satisfied with the rate of return on their investments.

2.Not Working Less and Traveling More

A study of 2,000 baby boomers commissioned by British Airways revealed that one out of five boomers regrets not doing more traveling around the world. The survey data also indicate that only 9% of American workers get more than nine vacations days per year and that only 37% of Americans took all of their vacation days in 2015, suggesting that working too much may be an issue whose scope extends far beyond just the baby boomer generation.

A 10-year research project conducted by Karl Pillemer, Professor of Human Development at Cornell University, into the lives of 1,200 people aged 65 and older also revealed that lack of travel during one’s youth is a common regret. He writes, “To sum up what I learned in a sentence: When your traveling days are over, you will wish you had taken one more trip.”

3. Not Working More

It might sound surprising given the decades of work they’ve done, but more than two-thirds of middle-income baby boomer retirees wish they had worked longer, and not for expected reasons. One might assume that people would want to continue working to keep earning their salaries, but for many baby boomers, wanting to keep working is about the work. People who are passionate about their careers and enjoy their work want to keep doing it. For this reason, many baby boomers return to the workforce on a part-time basis or as consultants. A number of baby boomers also enjoy working during their later years because they find that it keeps them mentally sharp, physically fit, and gives them a sense of purpose.