Positive thinking is somewhat a treasure to some of us. Some of us have blended so well with pessimism that positivity becomes alien and a virus.
We should understand that when you think positively, things will begin to change for the better. You will notice that your goals for the day will switch from things like "I am so bored and depressed today" to better things like "what can I do to make my day better?"
I never said it will be easy or simple but it will be a much better option. No one can make you happy and fulfilled than yourself.