On days when you can’t concentrate, ask yourself what’s been on your mind recently. Humans are naturally motivated to be curious about things we’re interested in. For example, many of us want to quit our jobs. If you’re thinking of quitting, read books written by people who’ve quit. There are many such books. If you want to emigrate, read stories about people who’ve moved across lands and oceans. If you’re struggling with low self-esteem, have lost touch with a good friend or feel depressed, seek out books about that.