An insurer's actuarists have determined that following this list of fifteen tips could add 77 years to your life, or least get you to the century mark.Follow this checklist of 15 tips and you could add up to 77 years to your life. Sound too good to be true? Not according to new research from Norwich Union. The insurer's actuarists have crunched some numbers that shows simple things like enjoying a good laugh and eating well can give a huge boost to your longevity.The list ranges from the fairly obvious - quit smoking - to the more esoteric. Who would have thought that flossing your teeth could add six years to your life?Here is the the list:1. Be married/live with a partner - add 1 yearNorwich Union data shows people who are married or live with a partner can expect to live on average a year...