Went out for a 70 minute run today and it took me about 3 and a half miles before I felt like I was running on all cylinders. Whats with this? Is it simply the colder weather? Any advice on how to warm up faster? Problem being after I am warmed up I can quite easily pump out a sub 10 min 1.5 miler but 'cold' I keep hitting between 10:30 and 11:00 which is shite. The 800m warm up they give you isnt enough for me! Please advise! J.