Burn Notice, Season 5

Michael:
[voice-over] For a spy, the worst thing that can happen is to become someone else's asset. You do anything you can to avoid it, making sure there's nothing people can grab onto and use as leverage. You move through life unattached, keeping the world at a distance. It's a hard way to live, but there's a cold logic to it. Love nothing, and nothing you love can be used against you. Once you violate that rule and make that connection with someone, you've handed your enemies the key to destroying you.