Cook missed out on his 26th Test century by just five runs but the English skipper said even though it was frustrating he was delighted to get out of poor form.
Cook marked his return to form with a dogged 95 while youngster Gary Ballance (104 not out) hit his second successive century as England reached a comfortable 247 for two against India on the opening day.
"Mixed feelings to sum it up right," said Cook at the post day's press conference.
"It was frustrating to fall five runs short of the hundred. But if someone had offered me 95 runs yesterday, I would have grabbed it with both hands. So I am delighted to get those 95 runs," a visibly relieved Cook said.
Asked if he had changed anything in his batting, Cook replied: "I was going to the ball a lot more than I have ever done in my career before this. That is something I changed. It was for the first time today and at certain deliveries I was going towards them. It was something different and it worked." Cook's 95 was his highest score since a 130-run knock against New Zealand in May 2013. Since then he had never reached the nervous 90s in 27 innings.
The highlight of the day was Cook's dour batting after he got reprieve on 15 when Ravindra Jadeja dropped a sitter at third slip off debutant Pankaj Singh's bowling.
"I had talked about going down fighting. You do need a little luck at times. Sometimes you have the best of luck and earn it at times. So the drop by Jadeja was lucky in that sense. But he had the last laugh in the end when he dismissed me," said Cook.
Asked if he had finally managed to answer his critics, he simply shrugged, and said: "You can never silence everyone or anyone. People had given me confidence and it was disappointing to keep letting them down.
"It is a sense of contribution to the team. As a batsman you are not scoring runs when that is your job and despite all the support you are still frustrated."
Thanks to his efforts and Ballance's third Test century, England are now in a comfortable position going into the second day.
Cook had words of appreciation for Ballance with whom he added 158 runs for the second wicket.
"It looks like he (Ballance) bats the same way in every innings and that is very impressive. When he first came into the side he was a bit nervous. But he has found his feet now and has a solid technique.
"He is a fine player and sticks to his method for a long period of time. That is something very important in Test cricket," Cook said about Ballance.
"It was a good day for us. 250-odd for two wickets is a great score for us today. We need to go big from here. The ball swung all day, every time the seamers came up to bowl.
"The pitch was easy paced today but it will get slightly quicker as the match goes on I think. Hopefully tomorrow we can build on our score tomorrow," he signed off.