I tried doing this in game, and it was really forgeted up.
On one brick:
[x] [0] [ ] [Onplayertouch] [client] [centerprint] [<var:pl:Health>]
On a second brick:
[x] [0] [ ] [Onactivate] [Self] [Dosub] [1] [1]
[x] [1] [1000] [Onsub] [Self] [Dosub] [1] [2]
[x] [2] [ ] [Onsub] [Player] [VCE_ModVariable] [Health] [Subtract] [1]
If you didn't know, the Sub events are basically relay events that have the Client and Player subjects.
I would stand on the first brick, displaying my health, then I would click the second one. And, for those of you who can look at events (like myself) and follow what they are supposed to do, you would assume that 1) <var:pl:Health> is a variable replacer, and 2) that this would reduced the player's health until they die, displaying the player's reducing health in centerprint. Well, nope. Ran it, instantly killed me, except it wasn't a normal death - the screen would flash red like normal, my player would do the death animation, but my body would disappear and I was still able to control my player. I was stuck like that until I did fly mode.
How did you reduce your health? Because obviously I did it a different way.