SWIMMING TIME!!!!!!!

I have few Chairi Symptoms and I want to excersize, not just because excersize is important, but because I want to look good, I am 24 years old and I want to look fit. This is where i a met with my first barrier. I have 10 and 15 mm herniation, very little pain no head aches no syrinx, been recommended by Chiairi specialist to hold off on surgery until neccessary, I DONT KNOW HOW MUCH I CAN LIFT, I will start with swimming, and push ups and sit ups and would like to do pull ups, but i am not sure if i can do that. I hope I will not bring on any pain or irritate things, this is my only concern.