"I have worked really hard for my up coming movie #RamanRaghav2 and I believe this is my best performance by far," he tweeted during a chat with his fans.
The "Bajrangi Bhaijaan" star says the prep behind a good performance does affect him personally.
"When you take something from a character you play, the character takes something out of you too," he said.
When asked who inspires him, Siddiqui named veteran actor Naseeruddin Shah his idol.
Directed by Anurag Kashyap, "Raman Raghav 2.0" releases tomorrow.