I'm vegan and am usually active throughout the day everyday. Is this enough?

I'm thin but all of my friends are getting gym memberships and keep telling me it's good to have a structured exercise diet regimen. Right now, I just eat a vegan (mostly raw foods) breakfast, lunch, and dinner and only more if I get hungry. I am usually doing various activities throughout the day and like to take long walks in the afternoon and I'm rarely am found sitting. Is this enough or should I be doing more?