Might consider a form of interval training if endless running (4-5 days a week...which can be muscle wasting in it's self) does not appeal to you. Something like the Tabata protocol for example, which is usually preformed 2 to 3 times a week. That's 20 seconds of intense effort followed by 10 seconds of rest and than back to the 20 second effort again, than 10 second rest, etc. Any where from 4 to 8 sets or cycles of this interval training, depending on personal goals..
Has worked wonders for fat lost while retaining, or improving, present muscle mass. Can be done with a rowing machine, airdyne, spin cycle (not a washing machine), elliptical machine, run/walk, etc. Works well for certain weight exercises also: squats, DL, cleans, etc. Even bwt squats give results. In any event, a killer method which should be approached slowly at first. But after a while fat lost and a higher level of stamina (endurance-strength) will follow.
Lot's of other interval training protocols that can give outstanding results other than Tabata. Take a web crawl and see what you may find. Many college, sports medicine and research information on interval methods and their affect on improving V02 max and fat reduction.. Good luck.
