Love for yourself and for others is the start of a path that leads to a lifetime of being happy. Sure there will be down days but you can't be truly happy unless you have love in your heart for yourself and those around you; anything else is an empty attempt at being happy and leads to anger and isolation.
Laughter is not an actual cure for anything, but it makes the pain and sickness feel better for a time. To laugh is to flood the mind with chemicals that will lower pain response and to a small extent help in the healing process. It sure does take the mind off of being sick or in pain.