When you borrow against collateral on a protocol like Aave, the protocol tracks a single number called the health factor. It compares the value of your collateral (adjusted by a risk weight) against the value of your debt. A health factor of 2 means your collateral is worth roughly twice what it needs to be. A health factor of 1 is the edge: one bad price tick and part of your collateral is sold to repay the loan.
The number moves on its own as prices move. You do not have to touch the position for it to become risky. A drop in your collateral asset or a rise in your borrowed asset both push it down. This is why monitoring matters: liquidations happen fastest during volatile hours, often while you are asleep.
To keep a position healthy, borrow well below the maximum, watch the health factor rather than the raw prices, and add collateral or repay debt before the number approaches 1. A cushion that felt generous in a calm market can vanish in a single volatile candle.