One of the pitfalls of positivity is that people tend to fantasize about a perfect life instead of realistically facing the fact that no life is perfect. Everyone's existence contains challenges, disappointments, frustration and failed expectations.
Further, what usually happens is that most of us become passive. We distract ourselves by watching more television or spending more hours on the computer. We wait for sadness to pass and we behave as if nothing bad is going on. Keeping up a good front is important in most people's lives, yet behind the facade can lurk a good deal of fear.
Instead of positivity, I think what is needed is reality. Being realistic means that you drop the main defense that all of us are tempted to employ - denial. The only reason to deny your sadness is if you feel that you can't do anything about it. It is perfectly normal to have sadness in your life. Some kinds, however, can be a cause for concern. If you are feeling sad at this moment, or have been experiencing a down mood for a while, look honestly at your situation.
Developing emotional resilience is perhaps the most important, because that is the ability to bounce back from the sadness. You have to encourage it by being present with you feelings instead of fearing them, by focusing on the times you have survived and thrived in the face of tough circumstances and by appreciating and rewarding yourself for dealing with your difficulties. Sadness comes and goes, working it on long-term to get emotionally mature happiness is the best way to insulate ourselves from downswings in our mood.
.. and it takes time and silence.
So, it is better to stay in silence for awhile to build your well-being and get yourself and mind back in one piece.