At What Age Should I...

I don't know what age you get to before you start saying 'Age ain't nothing but a number' but science has worked out at what age you should give up the idea of taking up learning Mandarin or when to expect to take delivery of that mid-life crisis sports car.
According to science, the age of 8 is the peak time to learn a new language while we are still able to adapt to a new language structure. 
If you are a female between 20 and 23, you are at the peak of attractiveness to the opposite sex, if you are female and 24 or older than those trips to the make-up counter may become a bit more necessary.
Creativity peaks at 25 so if you haven't written that book or painted that picture by your 26th birthday, well you still have four years to make it as a sports star as you are at your peak aged 30 with a mix of experience, tactical nuance and your body can still take the rigours of professional sport before you hit 31 and your muscles wave a little white flag in submission.
That said, you are at your peak for playing chess at 31 and nobody has ever pulled a muscle or strained a ligament moving a knight to F3.
As chess is a game for solitary types, it is the perfect practise for when men wake up on your 35th birthday as that is the age when males are at their loneliest but that passes within 3 years as aged 38 is when we reach peak contentment.
Strangely, six year later at 44 is when we reach peak depression and the classic midlife crisis looms as our declining powers become more noticeable and women buy tight, leather trousers and peroxide our hair and men buy a medallion and undo the top three buttons on their shirts.
Despite our declining chess ability, sagging muscles and rash from cheap gold chained jewellery, the age at which the average Nobel Laureate gets their award is 59 so this is the time to bring peace to the Middle East or revisit that great piece of literature that has been at the back of the drawer since you hit 44 and spent your time flirting embarrassingly with people 20 years your junior.