One of my colleagues jogs everyday. No matter how bad the weather is, he goes running in the heavy rain or snow. He either comes running to work from Shinagawa in the morning or goes out running around the Imperial Palace at lunch time. He's never skipped a day!! He never postpones running later than lunch time because then he might get lazy and can't be bothered to run anymore. Others were amazed by his ascetic determination. He says the key is to make it a habit and keep it as part of his daily routine so that it doesn't feel right when he doesn't. If he doesn't run he feels defeated and lost against himself. He is really impressive.
I agree that keeping a routine is the key to continuing. I was influenced by his self discipline and I decided to workout everyday at lunch time too. I either do my own core-training or GYROKINESIS® exercises. So far, I've been continuing for a few weeks and I feel really good about myself for doing it!! Satisfaction is probably what keeps me going.