Look at stocks as parts of businesses. Ask yourself, ‘How would I feel if the stock exchange was closing tomorrow for next three years?’ If I am happy owning the stock under that circumstances, I am happy with the business that frame of mind is important to investing.
The market is there to serve you and not to instruct you. It is not telling you whether you are right or wrong. The business result will determine that. I stole that one from (framed value investor) Ben Graham.
You can’t precisely know what a stock is worth; some leave yourself a margin of safety. Only go into things where you could be wrong to some extent and come out Ok.
Borrowed money is the most common way that smart guys go broke.
The stock doesn’t know you own it. You have feelings about it, but it has no feelings about you. The stock doesn’t know what you paid. People shouldn’t get emotionally involved with their stocks.