It took exactly an hour.
Just 60 minutes, but it was enough to potentially save the lives of three people.
Last Thursday I swapped my post work yoga class for a different feel-good activity instead – giving blood.
It’s something I did for the first time many years ago, but have lapsed in recent years.
And really I had no excuse, the donation centre is right next to the Telegraph offices in the city centre.
The staff were just as friendly as I’d remembered, and it was quick and painless, almost relaxing to lay back in the reclining seat and watch early evening television.
The only thing that had changed were the snacks, nowadays you are urged to eat something salty before donation rather than having a sweet biscuit afterwards.
Just a few days later came the news that Sheffield’s 8,000 blood donors are being urged to make and keep appointments at the donor centre before Christmas as NHS Blood and Transplant warns it needs to build up blood stocks ahead of the critical festive period.
There are still 700 blood donation appointments unfilled at Sheffield Donor Centre in Cathedral Court in the six weeks until the New Year.
Traditionally donations drop around November and December, as many are tied up with Christmas planning, and others forget their already-booked appointments.
This year there are also concerns that expected bad weather will mean others struggle to get to the centre.
And the impact could stretch far beyond Sheffield.
A serious drop in donations could affect the supply of blood to the tens of thousands of people in England who will need transfusions over the festive period as treatment for a blood condition or cancer, or due to surgery, childbirth or an accident.
Swapping an hour of festive shopping, drinking – or yoga – to give blood this winter could be the greatest gift you give.
The snacks are better, too.
Make, view and change appointments by calling 0300 123 23 23 or online at www.blood.co.uk