wisdom from yulgok-yi-yi 1, Only thinking about playing after work, on weekend, consuming pattern.- invest time for self-improvement. 2. Wasting whole day — you can avoid it by recording daily report. then you can see how you spent time exactly. 3. Liking only the people thinking same with you — there’s no development 4. Wasting life purposed on tasteful/elegant- don’t misunderstand about You Only Live Once.