That pic was a hot topic around here 2 years ago when T3 came out. Basically that pic was taken after he had been out of shape from heart surgery (he hadn't been able to work out like he used to), and he also had cracked some ribs in a motorcycle accident.
But Arnold pulled himself together, and got himself into great shape for T3: Rise of the machines. If you saw the Flex that came out around that time, he was doing a double bicep pose on his bike, and he also was posing a little on the behind the scenes footage on the T3 dvd. At 56 years old, heart surgery, cracked ribs, and a torn rotator I don't think 222lbs 9% bodyfat (In T3) is anything to sneeze at.
Since that pic you posted is 3 years old, and T3 is 2 years old, it's a safe bet that Arnold doesn't look like either of those forms currently. Probably somewhere inbetween. But with a whole state to run, and a family, I can't blame him for not looking like he did in the 70's or 80's. Then again, he's proved all there is to prove with his body, and won all there is to win.
As for the age thing, don't let that get you down. I know seeing a pic of a formal idol not looking their best can be a downer. But try to keep all of the above in mind, and also that is only Arnolds situation not yours. As you get older, just keep at it, and you'll have nothing to worry about
