Most find speculation and investing hard. It's because we are just not wired to be good at it. Almost everything we think we should do will hurt, and almost everything we believe will harm us won't.
This is a very acute observation, and it's a crucial one to understand for anyone who wants to succeed in the markets. Technical analysis does work (at least a good deal of the time, when applied correctly) but it's doubly effective when combined with a keen understanding of market psychology.
The bit from Warren Buffett about being fearful when others are greedy......it's a truism. Successful traders will tell you: when the market seems exuberant and can't possibly stop rising, it's probably time to sell. And vice versa.