Kone has been working with a personal trainer all season and devised his own schedule in South Africa to ensure his levels did not drop.
Martinez said: "When he came back from the African Nations Cup as a player, you've got a decision to make. Do you just go through the motions and wait for summer? After all, you've come back from a different environment and you're tired.
After all, you've come back from a different environment and you're tired.
"Or you say, 'I wasted a month of my club time. I'm going to get it back and finish strong'. That's the mentality he's got now."