I find it so much better to run outside rather than on a treadmill. I spent about 10 years pounding away in a gym. I used to run 6k in 40 mins 3 times a week. I had a complete break of about 5 years then started the c25k plan. I now run outdoors, it's so much nicer in the fresh air. I don't get as hot or thirsty and I feel like I can just keep running.
I'm up to 40 mins already and when I put my route in mapmyrun I am running 6.38k!
Needless to say I won't be wasting my money with gym memberships again!!
Good luck everyone