Too old to rock 'n' roll: Too young to die

Seems David Beckham is too old to be the Captain of the England football team. The man is only 35 right?
Is this decision right? I've never been a fan of the culture of youf and always hoped that at some point, as the population aged, this attitude would change.
My father recently retired. He didn't want to retire but at the age of 70, the company he worked for felt they could no longer risk letting him manage younger warehouse staff, drive a forklift (even though he'd managed to get his license only a few years earlier) nor deliver it's computers. So effectively he was pushed into retirement. I did think he was lucky that they let him stay on 5 years after the retirement age even though he's more than capable. His view was that he was actually not old and could do the job.
Now, don't start shouting at me for being unrealistic about the physical requirements for some roles... yes, yes wear and tear from age is a factor - Beckham perhaps can't run at fast and may be more injury prone and Dad was probably too old to sit in a warehouse directing younger staff to do the heavy lifting.
In IT it's notoriously difficult to get a job if you are over 40. Just before I came on maternity leave, my director announced he was only interested in designers who were under 25...hardly an incentive for me to rush back to work.
There must be many jobs that people who turn 65, or 60 could continue to do. So what are these people supposed to do after retiring for the next 30 or so years - seems to me there is only so much gardening to be done? What if they don't have enough money to last that long, still have mortgages to pay or even children to support? Has anyone out there started afresh after the big 4-0, 5-0 or even 6-0? I hope so as it would be nice to hear that it's not all doom and gloom once the greys start to appear.

P.S. I saw Beckham on the last Jonathan Ross show. I was amazed at how articulate he had become so at least with age came some wisdom. And OHMYGOD the man is just too beautiful.
P.P.S. There are people who have slogged hard all their lives, who would welcome retiring at 60/65 and with a well deserved pension. Trust me, I wouldn't want to take that away from them.