(Bloomberg) — As she nears 100, Irene Bergman has some advice for enjoying a long career on Wall Street: Don't do anything stupid.

Consider investment returns, the financial adviser at Stralem & Co. said in an interview at her New York apartment, where, surrounded by paintings from Dutch masters, she telephones her clients. While many investors nowadays obsess over quick profits, it's best to wait at least three years, or better yet, many more, before evaluating holdings. But don't be afraid of revising your thesis, she said. If thorough research favors a portfolio shift, have courage and make changes.

"The longer you're in the business, the more pessimistic you get," Bergman said in her soft voice, noting she thinks shares are too expensive right now. Still, "I'm able to get bullish, because when I look at a stock, I can imagine where it was 40 years ago."