Even if we don’t harbor negative emotions, we can still feel the effects of a negative attitude from the influence of others. These might be the people with poor attitudes, negative outlooks on life, or bad personalities in general. 

Allowing these people to stay active in your life is much like having a malignant tumor. At first, it might just be a slight discomfort, but if you don’t remove it soon enough, it may end up spreading and harm you.