I always get my yearly checkup and blood work done.
My grandfather died at 45 from a heart attack and he wasn't fat at all. My uncle had a heart attack on his early 50s. Also not fat.
I have been exercising for about 13 years or so (mostly running in that time span; also did p90x, tapout xt, and insanity), have been on the thin/regular side (finally bulking some recently as has been discussed today), and yet still somehow my HDL got down under 40. Genes count for a lot in your health unfortunately... Started taking niacin OTC. HDLs in the 50s now.