The man on the hill

There once was a man who stood on top of a high hill. Three travellers, passing in the distance, noticed him and started arguing about him.
One said: “I bet he has lost his dog.” Another said: “No, he is probably looking for his friend.” The third said: “I think he is just up there to enjoy the fresh air.”
The three travellers could not agree and they kept arguing until the moment they reached the top of the hill.
Then one of them asked: “Sir, may I help you, have you lost your dog?”
“No thank you, I haven’t lost my dog.”
The other asked: “Are you perhaps looking for your friend?”
“No sir, I’m not looking for my friend either.”
Finally the third traveller asked: “Are you here to enjoy the fresh air?”
“No, sir.”
“But…, what are you doing here,” the three travellers asked practically at the same time.
The man on the hill replied: “I’m just standing here.”