You have to accept that you'll never consistently pick the top or the bottom of any market.

So buy or sell when the price is good enough for you to meet your overall goal.

For example, I like XVG coin and wanted to buy some more. I had some BTC which I purchased at $4500ish. Been watching it go up while XVG goes down and last night I decided to make my move and sold my BTC at around $5300 while XVG was at around 100 sats.

Woke up this morning to $5600 btc and XVG down to 90 sats. Am I pissed off that I missed out?

No. Because I made my decision based on the fact that I would be more unhappy if I woke up and BTC had dropped while XVG had risen. And I would do the same thing again. So if you really want to invest in something then you have to take action otherwise you could spend all your time just watching the price.