Hi Chris welcome to the forum.
As Dottie says I am a little older than you and started diving at the age 66 had my first dive with Bull, Tiger sharks and others at the age of 70, went again this year and loved every minute of it. They are such friendly playful animals you cannot help but love them. If you have the cash you must try it some time, look up Roland and Beulah of African Dive Adventure. If you read the magazine Diver watch out for an Article by Gavin Parson who was doing an article for them while I was there. Should be in the October issue.