Hartley trained with the England squad earlier this month, working towards building his fitness back up, and could make his return to rugby in a pre-season friendly when his club Northampton Saints take on Glasgow on Friday.
"I'm confident I'll play rugby until I'm 50. I had no concerns, I surrounded myself with the right advice and here I am ready to play," Hartley told British media.
"At the time it was disappointing because you want to be involved in everything, you don't want to miss games. But once the decision had been made for me and we agreed on it, I made peace with that.
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"As soon as I took my foot off the gas and stopped trying to make it back every week, which I was trying to do, I felt myself instantly get better."
(Reporting by Shrivathsa Sridhar in Bengaluru; Editing by Peter Rutherford)
