The Shikker Dovid read a beautiful thought from a holy website known as www.emunadaily.com. He encourages all people to read it. The thought is taken from Mishlei “One who guards his mouth and tongue, guards his soul from troubles”
In Behaloscha, Bnei Yisrael ‘murmur” against Gd. Despite having the food they need provided, the cloud of the Holy One to lead them. They still complained. Was it from lack of food they complained? Certainly not. The Shikker Dovid opines that they complained because they were not happy or content with themselves. They were not comfortable or secure in themselves. They needed to feel better about whatever insecurity they had by complaining.
Our souls and mental health would be better when we hold our tongues and do not speak bad about others-but also ourselves, our surroundings or our circumstances.
ShikkerDovid 
next time you feel like complaining, be careful! someone near you may have an even worse situation, and your complaining will make him feel worse. it may even embarress you too or make you feel awkward. emunah is beleiving that when you are given a test, it is there to strengthen you (whatever doesn’t kill you makes you stronger)teach you, and make you appreciate what you do have. it is accepting g-d’s plan as “bashert” or “gam ze l’tovah.”
even with the cloud overhead, food provided, needs met, it shows how when man is given a hand, he asks for an arm. nothing is ever enough. there will always be someone who has more than you, just as there will always be someone with less than you who would consider you fortunate. also, according to rabbi schwartz, shlita, a messege he taught me that was very powerful- life is made of puzzle pieces. you may like soemone else’s piece, nicer colors, interesting shape, but it doesn’t fit into your puzzle. meaning, if you desire what someone else has, it won’t work for you, it won’t be to your benefit. hasem was the architect of the world, and he knows which pieces go where,
Its an important point you raise. One of the sins that our community has a tendancy towards, in my opinion, is in this area. We all need to improve in the area of Shmiras HaLoshen, myself included. Thanks S.D for giving me a bit of a ‘kick in the pants’ to do so!