I just want to highlight this post from Power Score
"The Player Perspective: I'm so glad I am a player in this. It's so easy as a DM to fall into the trap of becoming numb to what it is like running a character. As a player, taking damage is very harrowing! What seems like nothing to you, the DM, is a major ordeal for the player.
This makes me want to ease back on my own players quite a bit. It can be unpleasant when you are getting pummeled on a regular basis. Not that we are in this game at all, it's just eye-opening when your character is in serious peril."
As a GM, it's worth remembering how much it sucks to take damage when it's your guy. And that games where you have a bunch of disposable PCs for one player are a nice change because it's not your only guy getting whacked. When it's you're one of one it can be a bit stressful.
Just the threat of PCs taking damage or taking losses can be effective - and actual damage pretty concerning.