Wanyama thinks that the former Mathare United coach has brought a ‘bit of luck’ to Harambee Stars having gone 11 matches unbeaten in all competition since he took over in 2016 before the defeat to Sierra Leone in Nations Cup qualifiers.
"He's a great manager. He's brought in team spirit and everyone believes that every game is important,” Wanyama told Kwese-ESPN Sport.
"When we go out there everyone believes that we can achieve something, He (Okumbi) has also brought a bit of luck because we didn't have that much and also the winning mentality.
"The boys have changed a bit and we have a winning mentality now."
Wanyama will be out of Stars friendly against Mozambique on September 2 in Maputo, though he is looking forward to guiding Kenya to her first trip back to the continental scene since 2004.
"We still need to work hard, to try and win, and to try and qualify for the African Cup of Nations."
The Kenyan captain opted out of Stars trip to Maputo to recover from a knee injury sustained during pre-season with Tottenham Hotspur.