Emotions.
Too often we are expected to suppress 'negative' emotion and 'put on a smile' or 'not let it worry us'. I believe, If you want to chuck a tantrum like a 3 year old in a shopping centre because you're angry. By all means, go right ahead. You'll feel better after. If you want to scream at someone because they're making you angry, why not? You'll feel better after. If you're upset about something but don't say anything because it's 'not as big as someone else's problems' be sad, be upset. If it's big enough to you to make you feel that way, what does it matter what other people think? Everyone has their problems and that's yours. If someone says something you're not happy with, tell them. If they retaliate unreasonably and get angry because you're telling them how you feel, they clearly don't belong in your life anyway. You'll be better off without them. We still need to recognise when we are wrong and learn to apologise - not apologising for how we feel but how we make others feel. We are expected to hide so many natural emotions that make us human. Hiding 'negative' emotion doesn't make it disappear, it just means it builds until it changes you.