Minerva McGonagall counted many achievements in life which gave her a sense of satisfaction.
She become an Animagus at the age of 22. She knew that there were a handful of witches or wizards who managed it at a younger age, but only six other people registered in the past century.
Minerva's Patronus took the form of a corporeal cat. She developed enough control of the spell to be able to cast it, transform into a tabby cat herself, and then play with the glowing feline. She hadn't done that in years, but the joy-filled memories of frolicking with the ethereal creature were now an integral part of her casting of the charm itself.
Minerva held the title of Transfiguration Professor at Hogwarts for three generations of students. When she took over the post from Albus Dumbledore, at his request upon his elevation to Headmaster, she experienced qualms over whether she would live up to her predecessor's reputation. She'd like to think that in the end she left behind her own indelible mark.
For the 40 years that she and Albus worked together she had been the Yin to his Yang.
As the Head of Gryffindor House, she was often thrust into the role of mother, more times than she cared to count. She didn't know if she was necessarily always successful at showing her charges how much she really cared. Her dry humor often got lost on a fourteen-year-old crying when the 'love of her life' took someone else to Hogsmeade. She could now admit, with hindsight, that her fanaticism while in quest for the Quidditch House Cup may have clouded her judgement upon occasion. And yet, she beamed with pride at the number of times (seventeen) the cup had been awarded to Gryffindor under her.
As Headmistress of Hogwarts for 15 years, she oversaw unprecedented changes in the curriculum, and felt she brought about true inter-house unity.
The trading card Minerva held lauded her quiet rebellion waged against Amycus and Alecto Carrow as having undoubtedly saved the lives of countless children.
In her defiance of Tom Riddle through two wars, she knew that it wasn't only the lives of children she ended up saving. She dueled Voldemort himself during the final battle, surviving to tell the tale.
But even before that encounter, she partook in another moment from The Battle of Hogwarts that her Chocolate Frog card memorialized – and it was perfect.
"The only known Hogwarts Head in history to activate the charm created by the founders themselves, causing the animation of Hogwarts' suits of armor, and for the castle to defend its inhabitants against attack."