This was quoted by Stephen Hawking almost a decade ago and I completely agree with it. I have seen many people in my life who complain all the time and eventually I distance myself from them. All the negative emotions that accompany their constant nagging, complaints and gossip just drains my energy. Sometimes the things that these people complain are often meaningless. Do not waste your time worrying about things that you can’t control. The one thing that you can control is your thought process, take charge of it and stay clear of negative energy.
Jealousy and anger is another such trait. One should never engage in these but if you find yourself in the company of those who display these emotions then try to stay away from them. Utilize your time in doing good for others and to you. Life will be a much happy experience.