If an adult has an annoying habit, an addiction, bad character, or weighs too much, they're not going to change because of us.
Some things are specifically commanded or prohibited by Scripture. Everything else is permissible. However, not everything that is permissible is beneficial. As we mature as Christians, we understand some of the permissible things are even less beneficial than we once thought they were. Our natural inclination at that point--at least for most of us, since most of us are legalists by nature--is to make a rule where the Scripture does not.
No one cares what we don't like. And even less what we hate. Of course, no one can be positive all the time--nor is there reason to be, but I have for decades been praying to be a positive person who builds up people rather than tear them down.