According to Wikipedia...
"Five whys is an iterative interrogative technique used to explore the cause-and-effect relationships underlying a particular problem. The primary goal of the technique is to determine the root cause of a defect or problem by repeating the question "Why?". Each answer forms the basis of the next question. The "five" in the name derives from an anecdotal observation on the number of iterations needed to resolve the problem."
That looks like...
" I want to lose weight..."
"Why?"
"Because I don't feel confident"
"Why? (Is that important)"
"Because it'it's really affecting my social life"
"Why is that important?"
"Because I feel depressed when I dont see friends and family, or interact with any other people, or do the things I enjoy"
Its your mental and emotional health that are a priority, you want to live a better quality and happier life.
Or...
"I want to get healthier."
"Why?"
"Because I want to be a better role model for my children."
"Why?(Is that important)"
"Because my mother suffered from diabetes, and I dont want to be in a wheelchair when my kids are getting married. I want to set a good example so that they have a healthy happy life, and not set them up for health problems in their life"
So, it's the fear of your quality of life deteriorating, of suffering with illness, needing medication, not being able to enjoy everything you previously could. Of having a fairly painful old age and possibly an early death.
Or...
"I want to look-good-naked"
"Why?"
"Because I want to attract a partner, and I dont feel comfortabl doing that currently""
"Why?(Is that important)"
"I'm 40 years old now, and I don't feel like I'll ever meet a partner unless I can improve my health and feel good about myself."
"Why?(Is that important)"
"I want to have kids soon, I don't want to leave it too late."
So, starting a family is one of your main goals in life, you'll feel incomplete if you don't give it your best shot.