Should I start karate as an adult?

I apologize in advance because probably this question has been already posed here many times. I'm 22 years old. I have some minimum experience in a martial art: I had taken classes of taekwondo when I was about 10, but it was my parents' choice and I never really liked it, in fact as a kid I hated exercise in general. But now it's different, I genuinely want to start karate for a number of reasons that do not need to be mentioned here. Would my age be a problem? And also, do I need to be in a good physical condition before starting? I'm completely healthy but I wouldn't say I'm fit. I'm willing to do some pre-exercise if necessary.