Retired U.S. Navy Seal turn best-selling author David Goggins has a message to investors who think they have it all figured out amid 2019, which was highlighted by 20%-plus gains in the major stock averages.

Avoid complacency and stand clear of it at all costs by staying mentally disciplined and hungry to learn and grow more. That means continue one’s research driven pursuit of undervalued stocks, don’t be afraid to take gains on stocks that have climbed excessively and never forget that stocks never only go up in a straight line.

“One thing I try to do is to win the war of the morning. A lot of times when you get complacent in life it’s because you don’t have different goals set every day of your life,” Goggins explained on Yahoo Finance’s The First Trade. “We get to a point in life where we think we have arrived. We have this arrived mentality.”

Added Goggins, “When you have this arrived mentality, there is a finish line in your life. And once you get to this finish line in life you are done. I don’t have a finish line. I don’t stop when I am tired. I stop when I am done. We aren’t done until we are dead. I constantly have this pursue and attack life mentality.”

It’s hard to not think that most investors will enter 2020 with a complacent mindset.

The Dow Jones Industrial Average and S&P 500 have surged 28% and 21%, respectively, year-to-date. A household name that is owned in most equity portfolios, Apple (AAPL), has skyrocketed 78%. Household net wealth has risen nicely in each quarter of the year on the back of the strong gains in stocks and higher real estate values.

For the most part, stocks have been on autopilot all year long despite constant fears over the U.S.-China trade war and various tweets from President Trump. Credit for that goes to three rate cuts from the Federal Reserve and a U.S. employment market that continues to produce record lows in the unemployment rate.