"Today, celebrities are selling products ranging from digestive tablets to hair oils and what not. I thought if I do not do it now, then I would be left behind in the race," said Sinha, who was in the capital Saturday to launch the Markson brand of colour TVs, LCDs, laptops, desktops and DVD players.
Fondly known as 'Shotgun', Sinha's Bollywood career started with "Sajan". He earned rave reviews for his performance in "Raampur Ka Lakshman", "Kalicharan" and "Dostana", to name some.
The actor with a deep baritone had last endorsed Bagpiper soda in the 1980s, only to face criticism when he became health minister in the National Democratic Alliance (NDA) government.
Asked why he took such a long time before endorsing again, he said: "I was repenting all these years. Modelling or campaigning for a label is no sin. However, being a public figure I must have given it some more thought.
"I must have realised my responsibility that I would leave a bad impact on the country's youth. Hence, I didn't take up any advertisements."
The multifaceted actor also pointed out that the bitter experience had made him choosy.
"I have an impressive personality, wonderful voice and popularity... I was saleable but not available. Today I am available, but not for everyone. I have become very selective after my past bad experience.
The same holds for him as an actor too.
"As far as films are concerned I am getting offers. I would not dishearten my fans and have decided to do a film as well. As I said I would pick and choose and do movies once in a blue moon," said Sinha, who last wowed viewers in "Aan: Men at Work".