Jamieson, Fausset and Brown on Philippians 2:30

30. for the work of Christ--namely, the bringing of a supply to me, the minister of Christ. He was probably in a delicate state of health in setting out from Philippi; but at all hazards he undertook this service of Christian love, which cost him a serious sickness.

not regarding his life--Most of the oldest manuscripts read, "hazarding," &c.

to supply your lack of service--Not that Paul would imply, they lacked the will: what they "lacked" was the "opportunity" by which to send their accustomed bounty (Php 4:10). "That which ye would have done if you could (but which you could not through absence), he did for you; therefore receive him with all joy" [Alford].