Hal - worrying about "making it to XX years" is only a sure way not to get there. Relax, enjoy every day and challenge to the fullest, and you will have more pure enjoyment packed into your lifetime.... more, in fact, than many 100 year olds ever had.
Always try to avoid or minimize stressful situations as you get older (BTW, how are the dogs behaving?).....just joking!
Make sure you DO the things you like, rather than dream or just talk about them.
I knew 30 year-old "old men" - it was a mental attitude. Couldn't get off their fanny. I also know guys in their 80s still going strong - can't do everything like they could in their 20s, but still having fun, and doing their best to keep at it.
Also, grandchildren are a great way to keep young at heart - mine keep me hopping, and they consider me a "buddy".