Randy, I don't run marathons but I do a LOT of cardio!
In summer/fall I mountain bike, road bike, hike, sprint hills, backpack, climb,etc... In winter/spring I climb mountains and snowboard down them.
Probably 300+ days a year I do excessive amounts of cardio. Hours a day!
From Apr>Dec I lift 2-3x per week, just basics. Always power variations of Oly lifts.
From Dec>Apr I don't lift at all.
I came out the last ski season at 227lbs. , very lean. Right now I'm about 238lbs., pretty lean. Got abs.
I basically do what the above advice is saying.