I found a fantastic resource the other day at RealAge.com. First of all, you take the free RealAge test which aims to calculate whether you are biologically younger, older or the same as your birthday age. This is calculated by assessing over 100 different health factors from lifestyle to genetics to medical history.
About an hour after you have taken the test, a personal plan is delivered to your email box which contains complete information about how to make yourself feel younger, together with a list of the factors that are actually making you feel younger or older.
FYI, although my actual age is 48.2 years, my RealAge is 44.5 years, although that won't be strictly accurate because at the time I took the test, I didn't know my cholesterol levels and I'd forgotten what my last blood pressure readings were (although I knew from regular checking with a home monitor that they tend to be in the ideal to normal range).
However, despite all that, the things that are making my RealAge younger include: