Markets fall faster than they rise because fear is more liquid than greed. That is not a reason to freeze, and it is not a reason to "do something" for the sake of motion.
Three questions
First: did your time horizon change? If you still need the money in twenty years, a week of volatility is weather.
Second: did the cash-flow of the businesses you own change, or only the price?
Third: are you being forced to sell? If not, you have the rare luxury of sitting still.
A practical ritual
Write your plan on a calm day. Include what you will buy, what you will not sell, and how much cash you need to sleep. Then, on a loud day, read the plan before you open the brokerage app.
Panic is expensive. Process is cheap.
