Multi-signature wallet that requires multiple keys to approve a transaction. Set it up as 2-of-3, 3-of-5, whatever you want. This is how every serious project, DAO, and fund stores their treasury. If one key gets compromised, the attacker still can't move funds without the other signers. Takes 10 minutes to set up and could save you from the worst day of your life. If you hold any meaningful amount of crypto, stop being lazy and set up a Safe.