>What motivates a person to make the needed changes in life to be healthier?
I have been trying to figure that out for many years.
INTERNAL
For myself, my internal ( intrinsic) motivation comes from wanting to live a long time and having the body to do it. I do not want to fall apart as I age, so I believe that I have to exercise daily to prevent that.
Other internal factors include my desire to help others. If I figure out something about losing and keeping off weight, I want to share it with others. I believe that we need to pay it forward!
EXTERNAL
My external (extrinsic) motivation comes from the many sized clothing that is in my closet right now! I want to stay in the smaller sizes, so I periodically get rid of my larger clothes, the comfortable ones that fit no matter how much I weigh!  Other external factors include my vanity. I want to look good on the outside.
I believe for a balanced life, you need to feel good on the inside and outside.

HOW TO LOSE AND KEEP WEIGHT OFF:

Know about the calories in and calories out! Know that you have to burn off what you eat!

Know that portion control is really necessary to shed some pounds along with keeping a diary of what you eat/how much you exercise.

Know that you have to love the exercise plan that you do. So try some things that you like, even if it doesn’t  seem to be helping at first, eventually exercise will slim you down but it may take a lot longer than you want it to.
Try to tune up your diet. Eat more grains, low fat dairy and less meat.
Eat more good fats such as almonds and fish oil if you do not eat enough fresh fish

So check out your motivation to make positive changes in your life today, and begin to feel good about yourself and your internal and external motivation will flourish!