Some lessons you only need to learn once. Here's what I learned at my current working-class girl job this week:
#2. If you swing a plastic bag of garbage upwards into a trash bin hard enough, and you've packed too much heavy stuff into the bag, and you underestimate the increased upper body strength your new weight-training regime has afforded you, you can actually watch the handle snap off in your hand too late to realize you're about to punch yourself in the eye.
#3. Laughing with your co-workers is a requirement for getting through any kind of work day. The more laughter, the better. This is especially easy to achieve if you perform frequent acts of hilarity like punching yourself in the eye while tossing trash bags.