When Indian billionaire Ratanji Tata was asked by the radio presenter in a telephone interview:

Sir, what do you remember when you got the happiest in life?

Ratanji Tata said:
I have gone through four stages of happiness in life, and I finally understood the meaning of true happiness.

The first stage was to accumulate wealth and resources.
But at this stage I didn't get the happiness I wanted.
Then came the second stage of collecting valuables and items.
But I realized that the effect of this thing is also temporary and the luster of precious things does not last long.

Then came the third phase of getting a big project. That was when I had 95% of the diesel supply in India and Africa.
I was also the owner of the largest steel factory in India and Asia. 
But even here I did not get the happiness that I had imagined.

The fourth step was when a friend of mine asked me to buy wheelchairs for some disabled children.
About 200 children.
At the behest of the friend, I immediately bought the wheelchairs.

But the friend insisted that I go with him and hand over the wheelchairs to the children. I got ready and went with him.
There I gave these children the wheel chairs with my own hands. I saw a strange glow of happiness on the faces of these children. I saw them all sitting in wheelchairs, moving around and having fun.
It was as if they had reached a picnic spot, where they were sharing a winning gift.

I felt real happiness inside me. 

When I decided to leave, one of the kids grabbed my leg.
I tried to slowly release my legs, but the child looked at my face and held my legs tight. I leaned over and asked the child: do you need anything else?

The answer this kid gave me not only shocked me but also completely changed my outlook towards life

This child said:

"I want to remember your face so that when I meet you in heaven, I can recognize you and thank you once again....!!"