give of oneself
Give time and energy to an unselfish pursuit. For example, The minister's sermons always emphasize giving of oneself to the less fortunate. [c. 1920]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.