volunteer for

volunteer for (something)

To choose or offer to assume or undertake some position, role, or duty without being asked, directed, or required to do so. I know you didn't volunteer for this responsibility, but you've done an admirable job filling in after Jack left the company. She volunteered for the role, not realizing how much additional work it entailed.
See also: volunteer
Farlex Dictionary of Idioms.

volunteer for something

 
1. to submit oneself for some task without being asked. Ivolunteered for the job. I didn't volunteer for this.
2. to work as an unpaid volunteer for a charity, etc. On Sundays she volunteers as a receptionist at the hospital.
See also: volunteer
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • a bounden duty
  • bounden
  • bounden duty
  • do (one's) duty
  • do one's duty
  • jump in feet first
  • jump in with both feet
  • jump in with both feet, to
  • dive in
  • dive in with both feet
References in periodicals archive
If you volunteer for a period of time prior to applying to university or college it might help with your application.
Reimbursing a volunteer for volunteer-related expenses generally should not convert a volunteer into an employee.
It will also include a formal application form to officially register the volunteer for insurance purposes.
If you'd like to volunteer for a short-term preservation project while on vacation, check out the opportunities available through these nonprofit organizations:
Now with their children Jeremiah, 3, and Bella, 2, they're preparing to leave in October to volunteer for two years at the Farm of the Child, a Franciscan mission in Honduras.
What's more, when you volunteer for VITA, you help a family in your area, and that family receives a refund that will be spent in the community--strengthening the local economy while making the family less in need of other community resources.
The order and specificity this structure brings to CPAs' volunteer financial education efforts will enable them to confidently volunteer for the campaign, knowing they'll be asked to contribute only in the areas they know best.
Tom Petryshen, former Olympic wrestler and Canada District 1 IABC member, says, "As a volunteer for the sport of wrestling, I got to experience many aspects of the Olympic Games.
It may be sufficient to volunteer for any open position, but it is more likely that a guided approach will achieve success.
Other times they work for federally sponsored programs administered by the states, or they volunteer for organizations that assist the federal government.
The agencies responded that of course it wouldn't; who would volunteer for such drudgery as cleaning house for a bedridden person they didn't even know?
I thought, 'If I feel that way, I'll bet the other 60% of residents who aren't from Oberlin might feel the same way.' I'd been a volunteer for many years and saw an opportunity." She and her husband formed a committee, and out of it the Volunteer Clearinghouse was born.