Running on the treadmill has been going great. I like the fact I can practice speed work without feeling like an idiot. I never tried it outdoors because I thought people may think I had a problem if I suddenly broke out into a sprint for no apparent reason. I'm comfortable up to the 5.5 speed. I feel like I'm pushing it, but not overdoing it. I run between 4 and 5, and when a 'powersong' comes on, I increase to 5.5, run the entire song, then decrease back between 4 and 5. My workout is between 45 minutes and an hour. I want to take full advantage of the gym membership, so I've been doing arm weights 2 or 3 times a week. I run for 10 minutes to warm up, then using 8 pound weights (I drop down to 5 in the middle of sets if the 8 is too much) do 3 sets of 10 bicep curls, tricep curls, and flies, then hop back on the treadmill for 4 or 5 miles. I'm glad I've been able to adapt to the treadmill, but I'm still ready to get outdoors!