I began investing shortly before the 2008 crash, and promptly lost around 50% of my retirement money. I really wanted to sell at the lows, but kept my wits and my portfolio rebounded over the next year to be worth a little more than what I started with. I've made many mistakes, but try to avoid repeating them. My biggest mistake seems to be buying great stocks, then selling them for a small profit instead of hanging on for a much larger one. These are certainly "interesting" times to be investing!