Just stop checking your portfolio often and keep yourself busy with some other work. Stop visiting your twitter profile as well if you don't care about the price at all and are willing to hold your portfolio till the end of your life. Also, you need to check historical data to convince yourself that the correction is for short term and the market will recover gradually. This is how i try to be cool, and i see every dip as an opportunity to inject as much cash as possible to increase the size of my portfolio by buying the dip.