For over a year now, I have turned up to "interval training"down at my local footy oval and waited for the whistle.
Every Tuesday morning at 6am, come rail, hail or shine.
I have to be honest, it sucks.
It hurts. To work at a level where your heart rate is hitting over 90%........oh my. But it is not meant to be comfortable, I guess.
The idea is based around Fartlek (delightful name) which is basically run your heart out really fast for a period of time, then run at a slower pace for a time, and repeat that loads of times, till you think you are going to vomit.