Life is like a wave; sometimes we feel up and happy and some other times we feel down and sad. The important thing to remember is that we should not let the sad times overwhelm us and rob us of our positive energy.
The down times are for self reflection. These are the times when you need to sit back and reflect on things and thereby help change the course of your life for the better
The easiest way to feel good instantly is to let go of your thoughts. Mind is a machine that constantly churns out thoughts and when we are not conscious, our attention is completely lost in these thoughts. True freedom ensues when you become conscious of these thoughts and stop giving them your unconscious attention.
In life there can be moments when we feel that everything is lost and there is no way out. This is exactly the feeling a caterpillar presumably must be having when it is undergoing such massive transformation
Every situation in life has value and there is always something that we can learn from it. So instead of cursing a negative situation, try to focus on what it has to offer in terms of your personal growth.