We’ve all had this experience. There is a person A who is frequently unhappy about something. They complain about life, their kids, other team members, lack of promotion, too much work… You know who I mean? Here is what Leila Towne recommends:

Distinguish this from venting
Take “no-whining allowed” stance
Call people on it

I watched this short video and would like to recommend it to you. The video lasts less than 5 min and you will be glad that you invested time in watching it.