He told BBC Radio Lancashire: "I didn't have any problem proving my fitness.
"I'm happy here - I hope to score goals and if I'm fit I know I will have to fight for my place."
He added: "The Premier League is the best league in the world and I always wanted to stay here.
"I know Blackburn are a good team. I need to be playing to gain full fitness - I hope to play some friendly matches and hopefully I'll be match fit within the next month.
He's a little bit more experienced than our other forwards. hopefully we'll be able to get him in the pack as soon as we can Blackburn manager Sam Allardyce "It's going to be hard work because sometimes if you return from one injury and pick up another it's difficult. So I just hope nothing more will happen to me."
The Zimbabwe international, who spent the second half of last season on loan at Sunderland before being released by parent club Manchester City earlier this summer, began his career with Jomo Cosmos in 1999.
After spending three seasons with the South African side, he moved to Auxerre before joining Portsmouth for £4.1m in January 2006.
The Harare-born forward made over 70 appearances for Pompey before completing a move to City two years later.
Manager Sam Allardyce added that he is confident the Zimbabwe international will be a valuable asset if he can regain the form shown in last season's 4-1 win by City at Eastlands.
"Our objective is to get him playing like that again," he said.
"He's hungry to continue in the Premier League and we know apart from that injury what he can do. Hopefully we can rekindle that quality of play we know he has.
"I remember him starting well at Newcastle when I was manager there and he came with Portsmouth and within 20 minutes we were 3-0 down and he scored two of them.
"He's a little bit more experienced than our other forwards Mame [Biram Diouf] and Niko [Kalinic] so hopefully we'll be able to get him in the pack as soon as we can."