my lab's daily exercise

I have a Lab/pit mix that literally exercises himself everyday, be it outside or in. He gets these 'spells' where he just takes off running full speed, growling/barking and jumping over anything in his path. When he does that, it's excellent entertainment for us. lol We sometimes egg him on by acting like we were gonna get him and he goes into another running frenzy. His growling isn't mean, just playful growls/barks like he's telling us to join in. lol By the time he's done (takes him a hard 20min.), he's plumb wore himself out. Does this at least twice a day, more if he's outside.

well i dont personally walk my dog daily.. tho i make it a point to play with it for atleast 1 hour daily after i come.. about its other exercise.. it goes for a 4-5KM walk/slow jog in morning and evening.. and it eats like hell!