I think you have to learn that there's a company behind every stock, and that there's only one real reason why stocks go up. Companies go from doing poorly to doing well or small companies grow to large companies.
I've found that when the market's going down and you buy funds wisely, at some point in the future you will be happy. You won't get there by reading 'Now is the time to buy.'
It's human nature to keep doing something as long as it's pleasurable and you can succeed at it - which is why the world population continues to double every 40 years.
When stocks are attractive, you buy them. Sure, they can go lower. I've bought stocks at $12 that went to $2, but then they later went to $30. You just don't know when you can find the bottom.
You get recessions, you have stock market declines. If you don't understand that's going to happen, then you're not ready, you won't do well in the markets.
