This was a question haunting a small boy. Their parents were  at wit's end, as they could not explain it in a simple language the boy could comprehend.

Once the family went for a dharshan to Shri Ramana Maharishi. The boy put forward his question to Ramana Maharishi.

Shri Ramana laughed to himself. Then with smiling face, he asked his devotee to serve  the boy dosa from the kitchen. 

So, on a plain leaf, a dosa was served. Shri Ramana looked at the boy and said," Now I will say "Hmm" 

Then only you should start eating. Then again I will say "hmm" After that no piece of dosa should be left on your plate."

The boy agreed. He was so excited. Others were watching expectantly.  Now the boy  was eagerly waiting for the signal by looking at Shri Ramana's face. When he gave the signal "hmm" the boy started eating. Now his attention was on Shri Ramana. He wanted to finish dosa before the signal. The boy was eating dosa in a hurry , tearing big chunks of dosa,  but, all the time keeping his attention on Shri Ramana. The dosa was reducing in size gradually. There was a small piece left. The boy was looking anxiously  at Shri Ramana for the second signal. The moment he gave the  signal, the boy immediately put the dosa in his mouth. 

Now Shri Ramana asked him " where was your attention till now? On me or on Dosa?"

The boy replied " On both"

Shri Ramana said" Yes. You were actively involved in finishing dosa, with your attention on me. You were not distracted at all.

Like this when you do your daily activities with your attention or thoughts  on God in the back ground, it is known as meditation."

The two signals "hmm" are birth & death. Within these two events, one can engage in meditation, as demonstrated by Shri Ramana Maharishi. But to understand this we all need divine grace to mellow & mature. We all differ from each other and hence take different time to comprehend this great truth.