India, May 21 -- J ackie Shroff has been a constant in Hindi cinema for over 43 years, and remarkably, he continues to remain relevant - landing substantial roles and constantly reinventing himself on screen. Reportedly, the actor has joined the cast of Shah Rukh Khan's upcoming film King, adding yet another marquee project to his impressive roster. Lately, he's been on a roll playing characters with grey shades, like in Singham Again and last year's Baby John. Ask him why his negative roles seem to resonate so well with audiences, and Jackie replies with characteristic honesty: "I'm an actor - I try to do all kinds of roles, and I've been doing that for years. Early in my career, I did films such as Parinda (1989), 100 Days (1991), Mission Kashmir (2000), Samay: When Time Strikes (2003)... My first film had me as a hero, sure, but it was an anti-hero of sorts. He came from the underbelly of the city and went through a transformation. Whatever role comes my way, I just try to do it justice." He goes on to explain his process: "I listen to my technicians, I follow the script, and I bring in my sincerity and emotions. Whether it's the bad guy, the good guy, a cameo - I enjoy it all. I genuinely love my work, and when you love what you do, that connects with people." So what's his secret to staying relevant even today? "There is no strategy," Jackie shrugs, "I never plan or calculate. I work on impulse - I decide things on the spot. Sometimes, I take up a film because the writer's a friend or a camera person says, 'Do din ka kaam hai, kar le.' Sometimes it's because I need the money, or a big banner offers me good work along with good money." Importantly, he has no regrets about any of the choices he's made: "I'm not complaining about the kind of roles I'm getting. An actor should do everything, not just lead roles. A chair has four legs - take one away, and it collapses. I aim to be that pillar in the film, whichever one it may be. I'm doing a bit of everything and having a great time." Even today, Jackie remains one of the busiest actors in the industry - arguably working more than some of the younger stars. "I've never really thought about whether I'm doing more or less work," he laughs. "Back in the day, we used to juggle two or three films in one day. Now, I'm doing one film a day. And honestly, sometimes even that feels like a lot!"...