Only lost my work once. That was back when I was 15 and I formatted both my computer and my backup Zip disk because I completely forgot.

Thankfully it was only a couple of stupid Flash movies I lost (though I thought one was neat =/)

Since then, I have never lost work. I save very regularlly and I have a drive I save everything to which is saved onto a server and backed up nightly onto two additional hard drives. At any given time, I usually have 4-5 backups of my work and the backups are never older than one day. Not to mention I have a USP backup so if power goes out, I have plenty of time to save my work before my desktop would lose power (or, if I'm on my laptop, I can use the network for at least 6+ more hours so I am uninterrupted ).

To anyone who has lost work more than once.... well, shame on you. It's preventable.