There is no disputing that it is important to be positive. But what most people won’t tell you about is the importance of negative emotions.
I knew a guy who was potentially the most optimistic person anyone could meet. His resilience was like no other. I shall always recall the time when someone we knew had suffered a miscarriage. He said cheerily to her, “That’s not really bad news because it means you can still get pregnant again!”
It seemed as though he was incapable of feeling anything negative. Nothing would upset him–not even tragedies where people died. Then one day, something happened–one small event triggered something within him. Suddenly, all of those years of emotions that he suppressed surfaced all at once. It resulted in him having to take several months off work as he fell into a deep depression.
Resilience is part of being optimistic, but it doesn’t mean that they are both the same thing. And although trying to be optimistic is good, there are times when it could have an adverse effect.
Studies: one of the biggest contributors to psychological issues is emotional avoidance
It is human instinct to want to abstain from things that make us feel hurt. But repressing emotions such as sorrow leads to long-term issues such as depression or anxiety. For instance, if a loved one passed away, you should not give yourself a time limit to rush through the stages of grief. 
Many studies have proven that one of biggest contributors to psychological issues is emotional avoidance.
One such study  was conducted by Florida State University. Stress responses were measured by the heart rates of people who were alcohol dependent and exposed to alcohol-related cues. Those who restrained their thinking had much higher stress responses to the cues than those who did not suppress their thoughts.
Accepting and addressing bad emotions encourage a different kind of resilience. Some of these feelings have been instrumental in human survival since the dawn of time–whether it was fear (therefore the need to have better protection from danger) or the recognition that something didn’t feel good which motivated change.
How much optimism do we need? 
Too much or too little optimism is not healthy
There are good points to having an optimistic outlook as it helps you to identify opportunities and hope within challenging moments.
At the same time, having no optimism at all would mean that you may be unable to see a way out of problems.
There is also an unrealistic optimism where you may be in a state of denial about negative situations. For instance, someone with a gambling problem may simply keep gambling and tell themselves that they will win eventually (despite losing large sums of money).
Acknowledge some negative emotions are necessary
There are times when negative emotions are important. If a lion ran out in front of you, your fear is what would cause your survival instinct to kick in.
Remember you can adjust anytime
Not everything is within our control. Sometimes, you need to accept that and move forward in the best way possible–even if it is an option you do not like. You may have bought tickets to the theatre but there is a train strike. It could mean getting a taxi, and it’s ok to not feel happy about having to spend that extra money.
People who get caught in undercurrents while swimming often tend to panic and try to fight against the current, which only causes fatigue and drowning. Doing the opposite and going with the current will mean they can eventually swim back to the shore as the current will eventually weaken. Fighting against emotions that need to surface is the same.
It is ok to not feel happy or positive all the time. If you feel sad or have the need to cry–embrace it. Tears can sometimes be your body’s way of giving you a hug.
|||^||Lifehack: Why It Is a Lie That Time Heals All Wounds|
|||^||Scientific American: Negative Emotions Are Key to Well-Being|
|||^||Psychology Today: Emotional Acceptance: Why Feeling Bad is Good|