Pain is an essential ingredient in the growth and development of all humanity, this growth being more mental and spiritual than anything else. This may sound crazy, but it is true. While enduring physical pain makes one stronger and more tolerant physically, emotional and mental pain enable us to become more mentally and spiritually stable. Whichever type of pain is experienced, the experience is something that we carry with us always. With pain, there usually comes a lesson that is learnt; this we carry with us, as well.
There is a saying that states, "that which does not kill us makes us stronger." This saying is so accurate and true (even if it is a bit cliche) because survival builds strength, character and endurance. Survival of one's pain prepares or grooms us to endure the next pain that comes along. Pain and the survival of our pain actually give us the strength to move on. Some times we may take a while to recover from a specific pain, but we always do. The point is that once we have survived something that brings us pain, we will be better prepared for the next time.
Pain is not the same for everyone. No two people have ever, exactly experienced identical pain in their lives. People can relate to one another similarities and differences in their pain with others, but no one can claim to ever completely understand the pains of another person; this is just not realistic. However, pain experiences are all very individual and personal. In fact, individual and private pain is part of what make this world more diverse.
Finally, pain is necessary as a gauge by which humanity can measure against happiness and joy- all of the good emotions that we experience. Pain is the factor that makes us appreciate the good times and feelings. Without pain, we would have no basis for comparison, nor would we feel gratitude for the good things in our lives. Without pain, we would have no basis for comparison with when times are good, nor would we know to be thankful when things are good. Being thankful for the good in our lives is important in human development, as well.
In the end, no human being escapes the enduring of pain. We need our pain; it is a large part of who we are. This is what makes us human beings and make us the people that we are individually, whether we like it or not. While pain may be an unpleasant experience, it is a necessary one.