Make sure your expenses are lean. Hopefully you should have some margin in case things get tight, or so that you can shovel cash into the down market. Passively cultivate opportunities and keep your resume fresh, even if you have no interest in looking for a job right now.
As far as being mentally prepared for the numbers to start dropping, remember a this: Recent history has shown that the United States Federal government serves equity holders of United States companies above absolutely all else, and so the smart money is almost always on US equity. In the last recession, the housing market, job market, and stock markets all crashed and the government rushed to rescue the stock market above all, and to tremendous success. By contrast, consider what they did for the housing market, a tax credit to gin up demand. A credit that had to be paid back mind you. (The bailouts had to be paid back as well, of course, but corporations have also had access to virtually free capital courtesy of the central bank for nearly a decade)
Look at 2017. It took some last minute circus theatrics to defeat a bill that would have stripped healthcare from millions of working Americans. By contrast, a tax bill was much easier to pass. One that paid a few hundred bucks to laboring Americans in exchange for massive cut in corporate taxes, a vast majority of which is being used for share buybacks, thus returning even more to the equity holders. Doing this will send the deficit over a trillion again, despite the current congress being "very concerned" with deficits.
When you realize this, the idea of selling your equity at a steep discount is a complete non starter.