What’s the one mistake even the most successful women make repeatedly when it comes to their personal finances? According to Sallie Krawcheck, CEO and co-founder of Ellevest, a digital-first, mission-driven investment platform for women, it’s not investing enough.

“Our problem as women is that we don’t invest enough,” said Krawcheck, during a session at last month’s Women in Retail Leadership Days virtual event. “That’s the overwhelming, No. 1 mistake we make.”

Krawcheck added that a key reason women don’t invest is because they spend too much time trying to be perfect. “We wait,” noted Krawcheck. “We have to find the right place. We have the find the right relationship. We have to read the right book on investing. We all like to get our A’s, but waiting can cost you, over time, from $100 to $200 per day because of missing out on the compounding.”

Krawcheck suggested that women should really make an effort to invest. “If you’re able and if you feel confident enough in your financial situation, take 1 percent [and up to], 10 percent of every paycheck [to pay] yourself  through investing. You can take that money off the top of your income and have it working for future use.”

During the wide-ranging and interactive session, Krawcheck also discussed her illustrious career on Wall Street (she was the CEO of Merrill Lynch, Smith Barney, U.S. Trust, Citi Private Bank, Sanford C. Bernstein, and CFO for Citigroup); why she founded Ellevest; some general investment advice on how to prepare balance sheets for the year ahead; and much more.

To watch the full session with Krawcheck, as well as other exclusive on-demand content from the virtual event, register for Women in Retail Leadership Days. Today (Dec. 2) is the last day attendees can access on-demand event content.