Imaam Shafee (May Allah always bless him, Ameen) said: I used to spend time with the pious and wise.  i found two advices to be extremely relevant and beneficial:

• Time is a sword. You either take advantage of it by using it wisely or it will cut you .

• If you do not keep yourself occupied with good things, you will engage in evil (and foolish things.) (Risalatul Mustarshideen, Page 36 {paraphrased})