Short Answer: Lifetime status is essentially about miles flown, not miles earned. (This is the prevalent idea for just about every lifetime frequent flyer program with the exception of American.)

Long Answer: It's elite qualifying miles prior to 1/1/12, and only UA/CO revenue base flight miles (with 500 mile minimum per flight) since then.

Things that do not count:
-credit card miles
-class of service bonus reedemable miles
-elite bonus miles
-miles flown on award flights
-(past 1/1/12) partner flight miles
-(past 1/1/12) 50% EQM bonus for booking full fare/premium cabin revenue tickets (or any other EQM bonus)