This is a very important factor. Write down your good intention(s), preferably in a place where you often get to see them, like in your agenda.
When you look at your intentions and wonder "how am I going to make all this happen?" you probably have not been very realistic.
No problem, just take another look at your list and choose one or a maximum of three intentions you will be focusing on.
By talking about your intentions, they no longer remain ideas in your head, but actually become concrete. Your family and friends can also support and encourage you to stick to your intentions.
It's not because things aren't 100% perfect that you have failed. On the contrary, adopting new habits is a learning process, a small dip once and a while is part of it.
This means that you can measure the success of your goals. The more concrete your goal, the greater the chance of success.
I want to eat healthier in 2019. This is anything but concrete and cannot be measured. It is better to say: I want to have breakfast every day. This you can check and if you do not succeed you can check what the cause is and what the solution could be.
Reward yourself when you have achieved a milestone and think of something that you would like and can only buy or do when you have achieved your goal. This creates a nice win-win situation because you achieve your goal and you get something nice in return.