To answer that question, please read the linked article.
Her Majesty The Queen is a remarkable woman! And all the more remarkable that she continues to follow such a schedule at her age, when even HRH Prince Philip, Duke of Edinburgh, has stepped back from public life (of course he has that luxury, not being the reigning Monarch… but still!).
I wonder if those who presume to castigate Her Majesty, and the Royal Family, for being a drain on the public coffers (which is not true, but that’s another story) do even half so much, themselves – and all of it to benefit others?
May God grant her continued health and long life!
P.S. And as this essay notes,
“Plus don’t forget that apart from the United Kingdom of Great Britain and Northern Ireland she is also Head of State of other Countries… As of 2017, there are 16 Commonwealth realms: Antigua and Barbuda, Australia, Barbados, Belize, Canada, Grenada, Jamaica, New Zealand, Papua New Guinea, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Solomon Islands, The Bahamas and Tuvalu.”
She is also titular head of the Commonwealth of Nations itself, a loose alliance of 52 nations and some 2.4 billion people, mostly made up of nations formerly part of the British Empire. The role carries no legal or political authority, but she serves as a focus and symbol of unity for the Commonwealth, and exercises a certain degree of moral authority. To do so effectively, she must also keep up on the doings of the Commonwealth, and its member nations.
None too shabby, for a 91-year-old woman!