From my POV...
Age 5: Don't 'overpull' the drawer. I lost a toenail and two months of my life (spent in agony...) because of that.
Age 10: Don't try to mediate a fight between 2 other 10 year olds. Particularly if they are boys (girls don't get vicious until they hit their teens). Did just that and spent the whole day crying because one of the little $#*!%& decided to slap me across the face.
Age 15: Don't be tempted to jump out of that window if life throws you around like no tomorrow. Things will get better. It did for me and I am glad I didn't listen to the window.
Age 20: That procrastination is the root of all evil. Not money, not greed, not lust, not women. Which is why I better go back to studying because I've got a Genetics exam on Thursday and I have 6 weeks of lectures to go through AND I'm still posting/browsing three different forums at once.
Not good at all...
ETA: I misread this post's title... I didn't see the bit where it said '
a lesson'
