When it comes to financial advice, you could do worse than listen to someone who helped steer more money than almost anyone else on the planet.

When he was chairman and CEO of investment giant Vanguard Group, Jack Brennan oversaw a company that has since grown to over $7 trillion in assets. That torch has since been passed but Brennan still has plenty of wisdom to share in his new book "More Straight Talk on Investing," a follow-up to the 2002 edition.

He sat down with Reuters to talk about how to pace yourself for the long-distance race of financial security.

Q: Investors since 2000 have gone through so many different types of markets; how should they navigate all those ups and downs?

A: It comes down to simple stuff. Do your homework, be disciplined, be skeptical in avoiding fads, keep learning. Those are four elements I tell people all the time.

Q: Many young investors these days are getting market exposure by buying individual stocks on apps. Does that give you pause?

A: I worry about it a lot. It's like March Madness on TV. I don't get it, personally. If you want to speculate on some individual stocks, fine, but your core serious money needs to be in a diversified program. It's very hard to beat the stock market. There's an old joke that the quickest way to make a small fortune is to start with a large one, and then trade a lot.

Q: What advice do you have on avoiding classic investor biases and mistakes?

A: We are all subject to emotions when it comes to investing, so there are a couple of things that are very important. One is to tune out all the noise. You shouldn't really care about what is happening today, or this month, or even this year. I'm 66, and I hope I still have a 30-year time horizon. The second thing is that once a year reaffirm what you're trying to accomplish. Think about the issue in buckets: Short-term resources, intermediate goals, long-term goals. Once a year, maybe on New Year's Day, sit down and look at it all. You don't even have to do anything about it, but stay engaged.

Q: The market is around all-time highs, so any thoughts on where we stand right now?

A: The market is fully valued, in my opinion. I think we will come strongly out of this pandemic, and there are a lot of reasons why equities are still an attractive asset class for most people. You also enjoy the growth of those underlying companies and valuations.

Chris Taylor writes for Reuters.