It's actually quite rubbish! You have to do a really, really emotional scene with a tennis ball.
You know at some point they're gonna put in a person or a robot but when you're doing the scene you're like 'I love you tennis ball!' - 'I ain't never met a tennis ball like you.' It's just hard!
Were you a science fiction kid?
I was actually a science kid - I loved science. I always had dinosaurs around the house. Not real dinosaurs - my family couldn't afford real dinosaurs! But pictures and stuff - I loved science.
Science is where my future was gonna be but as the acting and music and performing began to develop, my love of science blended into a love of science fiction.
You said last year you were going to give up being an action hero in 2006.
It's not like giving it up but your knees tell you you're not gonna be an action hero forever.
They say to you in the morning: 'Listen man, we're not gonna jump over anything today - you need to adjust the scene so you're sitting down talking to these robots!'
It's like your body rejects stuff a little more. I pride myself on running - I look cool running. I don't ever wanna do the old man run - you know you see actors who do one movie too many.
Are you going to do any more music?
Yeah, I've got another single - my first in a few years - coming in five or six weeks and a new album in November/December. I'm stepping back in the ring!
What's better: music or movies?
There's nothing that can compare to music - just being on stage in front of 70,000 people - in that first couple of seconds of the record when the audience recognises the tune.
What do your children think about you saving the world again and again??
My son said: 'Daddy, I love I, Robot but don't save the world no more. I'm six years old - you've saved the world four times already!'
But a lot of black people don't get to save the world in movies so I think it's important that as an African American that I save the world.
Catch Will's chat with Adam on NR Showbiz on the CBBC Channel on Saturday 7 August.