The Kungfu we teach is not for contact fighting or sparring: we teach the forms as they have come down to us through the lineage of Chinese opera, which was for performance rather than sparring. The fights had to look good on a stage, so the essential lines and character of the martial art were preserved, the postures were slightly enhanced and emphasised (fighting doesn't have to look good, so kicks and postures do not have to be high or flashy, they just have to connect).
The result of this is that the underlying principles are unchanged and the forms are done for effect: in the opera they were done for the effect of the stage performance but we do them for their effects on the body. These include coordination, flexibility, good posture, a lightness of body, agility and strength.
Of course this means the forms in Kungfu are more strenuous, so if this poses a problem for you at the moment, then Qigong would be best...but who knows? Once your health improves with Qigong you might like to try out the Kungfu. It's more Yang in character: more exciting, more stimulating, lots of fun. There are weapons to play with such as the staff, the short staff, the broadsword, the straight sword, the spear. And the forms can be performed by people of all ages and levels of ability: the forms can be adapted for purpose. It's like selecting a gear when you drive: lower to start off, higher once a certain momentum is achieved.