You are as old as you consider yourself, and it is never, ever too late to do anything! All you need is the will and the energy, and even the energy can be manufactured.
There's a wonderful poem by Henry Wadsworth Longfellow, that I wanted to share.
Never Too Late
'It's too late!' Ah, nothing is too late-
Cato learned Greek at eighty, Sophocles
Wrote his grand 'Oedipus'; and Simonides
Bore off the praise of verse from his compeers
When each had numbered more than fourscore years.
And Theophrastus, at fourscore and ten
Had begun his 'Characters of men'.
Chaucer, at Woodstock, with his nightingales,
At sixty wrote the 'Canterbury Tales.'
Goethe, at Weimar, toiling to the last,
Completed 'Faust' when eighty years were past.
What then? Shall we sit idly down and say,
'The night has come, it is no longer day?'
For age is opportunity no less
than youth itself, in another dress.
And as the evening twilight fades away,
The sky is filled with stars, invisibly by day.
It is never too late to start doing what is right.
Amen to that!