How to get a lean muscular male body?

I'm 19 and I've been doing martial arts for 6 years but have stopped for 6 months due to a meniscus tear injury in my knee. I've lost a bit of muscle during my recovery and haven't worked out! I have athlete's guilt of not working out! I still love what I do but injuries happen and it won't stop me!I want to climb up and reach that calvin klein or boss model body type again. I mean if Ryan Reynolds and Brad Pitt change their bodies in less than a year to play a role in movie then I'm sure I can too! How can I adjust my work out from scrap?