Lazy Vizsla

Is there such a thing as a lazy Vizsla?  Normally when someone thinks Vizsla, your thoughts are high-energy, crazy, hyper.  Well lately Ralphie doesn't seem to be the typical Vizsla.
Ralphie has been very laid back.  I guess you can say sort of lazy.  Oh, today he did swim a little in the pool, chased a few lizards, went on a short walk and that's about it.  He's not interested in chewing his bone.  He just ended up sprawled on the sofa, sleeping after his minimal exercise.   He doesn't have much interest in the dog park as before.  Yesterday he played pretty much by himself at the park...wasn't interested in the other dogs.  He seemed happy and content just fetching the ball and playing frisbee with me and then he got hot and tired.  Can Ralphie be bored with the dog park?  I thought all dogs love running around with other dogs.
Is he getting to the age that he's slowing down?  He's soon to be two years old.
Can it be the weather?  Summers are very hot here.  Maybe the heat is draining him?  But then again I thought Vizslas are made to withstand hot weather...LOL
Can Ralphie be too domesticated...LOL...having the life in air conditioning with a nice clean fluffy bed,  able to stretch out on the sofa anytime, has treats of all kinds, toys of all kinds, has a cool pool to take a dip anytime.
Gosh, is this all normal?  LOL