take it upon (oneself) to (do something)

take it upon (oneself) to (do something)

To decide to do something even though it is not one's responsibility. I took it upon myself to print out these information packets for the meeting since I knew the data might be confusing. The kids took it upon themselves to wash your car—I'm so proud of them for doing it without being told!
See also: take, upon
Farlex Dictionary of Idioms.

take it upon oneself

Also, take on oneself. Undertake something, as in I took it upon myself to count the precise number of children in the audience, or She took it on herself to enter a convent. [Second half of 1400s]
See also: take, upon
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • take it on (oneself) to (do something)
  • take it on/upon yourself to do something
  • at (one's) expense
  • at expense
  • at somebody's expense
  • at someone's expense
  • at doorstep
  • at (one's) doorstep
  • a ball and chain
  • ball and chain