Too much stress cannot be laid...upon the admonition that we seek so far as possible to live in the lives of other people. By sharing in the misfortunes of others, and rejoicing in their happiness, you add to your own emotional serenity and stability.
This is the best possible way to retain important details that you wish to remember in any unified field of knowledge, whether it be the field of economics, science, history, or any other--link them up with related items which you already know or wouldn't mind knowing.
INTEREST. Here is the key to the whole thing. If and when you are truly interested in what you are doing, or are about to do, then you will center your attention on it with little or no effort, and almost irrespective of the attendant conditions.