How can one achieve incredible chakra such as that of the Third Raikage or Kisame?
There are times where a genius is born. It doesn't have to be in raw chakra, but in skill, brains, willpower, etc. 

Itachi for example is considered a genius, a fast learner, combat analyst and very powerful.
Madara is a genius. Awakening the Mangekyo, having power many shinobi feared.
A's father can also be considered a genius. Steel skin and iron blood, along with the incredible chakra and durability to match that of the Eight Tails. 

Kisame is a slightly different case. He's definitely fearsome strong, but his gigantic chakra reservoirs actually came from his sword, Samehade, which has the ability to consume the chakra of the victims it hits.