Let me share my regret:

At 13, I was doing some martial arts. The GURU was teaching how to tackle different difficulties, like how to block a punch, a kick, a low kick etc. But I was bothered much by PAKETMAR (pick-pocketer) who regularly trouble a lot of good people in the "office-time" crowd. I was curious to know how to catch a Paketmar if he is running away faster than me while chasing. The GURU told me "It is very easy, just touch his leg by your toe-tip, he will fell down". I could not believe this.

A few days later, we were in running practice, but I was still curious how the toe-tip trick could make a person fell down. I decided to check if the GURU was right. So, I extended my step just a few inches more while running so that I could touch the front runner's heel by my toe-tip, who was one of my best friend in that group. ALAS, he felt down so badly, I could not believe it. He got scratches on his knees and palms. I helped him to get up, but he immediately threw a hateful look and asked me "[Disallowed String for - use not allowed] kina chhirki hanya?" Uff, I did not have a answer, neither could I tell him that I was testing the GURU's idea. I still feel ashamed over my act whenever I remember this incident. He is still my good friend and is in regular touch, but this incident comes while all of us are in joking mood.