Consistency
Many times we start something and we are good for about 2 weeks, but then we miss one day. We pick it back up the next day and continue for about 3 more days and miss another. Before you know it, a month has passed and we have missed a total of 10 days.
The very first time you missed, you gave yourself permission be inconsistent.
The only way to make it a lifestyle is to be consistent. To make an effort over and over and over. Even when you want to quit, you have to be steady, unwavering. It has to become your very nature. You may even have to talk to yourself to convince yourself that this is necessary. There is a purpose.
I had to make a conscience decision to work out every day except weekends. I have decided to work out every morning and then walk 2-3 miles every day in the evening. So far, I have been consistent.
God has called us to a life of consistency with Him. There is no difference. Our determination has to be the same. We have to make it a lifestyle, not something that we pick up and put down at any whim. The same with exercising, you may not feel like it at first, but as time goes on, you will begin to see and feel the results.
1 Timothy 4:8 says, "For bodily exercise is only little profit, but godliness is profitable for all things, since it holds promise for the present life and also for the life to come."
Give yourself permission to be consistent. It is necessary.