The 32-year-old came off the bench to score twice in eight minutes, his first goals since January, in the 4-0 EFL Cup win over League Two Yeovil.
"I am really happy for these two goals but I am more happy for the team because a victory is important," Kone said.
"For me it is very important as a striker to score goals and I have to score to keep my confidence.
"I am feeling very well now but I am not 100 per cent, I think I am now about 70 to 80 per cent.
"Last week I was with the team, before I was with the physio to do my training because in the holiday I had an operation on my knee.
"I was very unlucky with the injuries but I am very positive in my head and I have to give 100 per cent for myself and this club."