Isaac, an elderly, very thin looking man, sees an advert in a Haifa newspaper: 

EXPERIENCED LUMBERJACK REQUIRED IN HAIFA

So he applies for the job and a week later he is asked to attend an interview in Haifa with the foreman.

During his interview, the foreman says to Isaac, "I can't help but notice your age and your body build. Are you sure you're a lumberjack?"

"Yes, of course I am. Would I have applied if I wasn't?"

So the foreman gives Isaac an axe, takes him outside, points to a sapling growing near them and says to Isaac, "OK then, lets see you chop this down." Isaac walks over to the sapling and with one blow of the axe chops it down.

The foreman then points out a larger tree and says, "try this one, then." Again, Isaac walks over to the tree and cuts it down effortlessly with one blow of the axe.

The foreman is amazed, but tries one more time. Pointing this time to a really large tree with a thick trunk, he says to Isaac, "OK, try this one then if you can." Isaac walks over to the tree, takes a deep breath, swings his axe and with one swoop, the large tree comes crashing down.

"I can't believe what I've just seen you do," says the foreman. "You're fantastic. Where did you learn to be such a great lumberjack?"

"Well if you must know," replies Isaac, "I worked in the Sahara Park for a long time."

"Don't you mean the Sahara Desert?" asks the foreman.

"NOW it's a desert," replies Isaac.