Prof. Mills died on July 24, 2012, at the 37 Military Hospital, three days after his 68th birthday.
The former President would have turned 77 today, July 21, 2021.
To depict out of sight was not out of mind, Mr Mahama took to his social media page to pen a brief message in his honour as he mourns him.
Mr Mahama wrote: Happy birthday Prof. Continue to Rest in Peace.
He backed his message with a lovely photo with his former boss which saw them beam with smiles.