"You are one insane tennis player, miles better than me, but I just want you to know that today isn't only a sad day for you and your team, it's a sad day for the sport and for everyone you've had an impact on".
"At some point when you feel like you're never going to get back to 100%, you've had the success that Andy has had, you can only understand the decision".
"Once you see the end in sight, I guess it would be harder to get motivated".
Murray faces a first-round clash Monday against in-form Spaniard Roberto Bautista Agut, seeded 22, who beat Djokovic on his was to winning the Qatar Open earlier this month.
Dr John O'Donnell told BBC Radio Five Live's Sportsweek programme: "I don't think it is impossible, but it will be very hard".
Murray's support for women and the women's game was also appreciated by Konta, who said: "There have been so many examples of when he has stood up for us - not just for women's tennis but women in general. That won't happen now". 'If it is my last match, I want to try and enjoy it - enjoy the whole experience, which is maybe something during my career that I've not done.
A super fan posted on Instagram describing her love for Murray after seeing his practice match with Novak Djokovic. "But you can't manage that". But he's 31. 10 years ago, if he retired at 31, we will say he had a great and very long career. "I think you also need a little bit of luck". We shared the court in the most important stadiums in the world, competing for the most important things. His birthday is one week before mine.
"Tennis will come to an end for us all but the friendships will last a lifetime", tweeted tennis player Grigor Dimitrov". She plays unseeded German Tatjana Maria in her first round match on Tuesday. "I hope he can finish strong and healthy", he said.
"I know how not well he was", said the Swiss. I am happy with it... But it was for a good cause. Now I can say I'm a real number one.
"In the middle to the end of December in my training block, I spoke to my team, and I told them, 'I can not keep doing this.' I needed to have an end point because I was playing with no idea when the pain was going to stop". I want to do it as long as I can and give myself the best possibilities to fight for the things really I am passionate about, and to keep doing the things that I really enjoy doing.
HIBS have paid tribute to Sir Andy Murray for his "incredible" career and the help he has offered two of the club's rising stars.
"But being honest, when somebody like him, that he achieved nearly everything in his tennis career, is suffering like he's doing for such a long time already ... probably he does the right thing for his mental health". "But is a little bit different because previous year I had about 10, 15 matches before Melbourne, now I have only one, which I lost it".