'Zero' is actress Anushka Sharma's fourth film with Shah Rukh Khan. She says he is the most giving artiste and that she has done some of her most challenging roles with him.In a social media post on Thursday, Anushka recounted the "beautiful coincidence" that 'Zero' is for her.I realised this very recently and I had to put it out. I started my career with you Shah Rukh and it's really beautiful that on my tenth anniversary as an actor, we are releasing our fourth film together," Anushka wrote.The actress had started her film career with Shah Rukh-starrer 'Rab Ne Bana Di Jodi' and has featured with him in 'Jab Tak Hai Jaan' and 'Jab Harry Met Sejal'.In a message to SRK, she said: "I would like to say that you are the most giving actor that I have worked with. It is strange and beautiful that I have done some of my most challenging works with you."In the journey of our four films, I have seen myself grow and I have seen you being there and showing the same enthusiasm and support for me to shine."'Zero' is directed by Aanand L. Rai, writer Himanshu Sharma and actor-producer Shah Rukh. In the film, releasing on Friday, Anushka essays a woman with cerebral palsy."It is incredible that they have dared to dream, dared to think that they can create something so spectacularly new. It is one of my most challenging roles and thank you Aanand L. Rai for believing in me, for letting me create Aafia on screen."On her character, Anushka said: "She is an embodiment of strength, happiness, resolve and love and I am so proud to present this incredible person to you. I wish this world had more people like Aafia."She thanked the team, including actress Katrina Kaif, for making "a dream turn into a beautiful reality".