Inside you there are two* lungs.
Feed them both a mixture of O2 and Nitrogen, with maybe 2% CO2 (I think?) and optionally a few trace amounts of other non-toxic gases.

(WARNING: The above describes a process known as "breathing", which can lead to death or other adverse side-effects. Consult a doctor or pharmacist to determine the exact amounts of O2, Nitrogen, and CO2 that are right for you. Offer void where prohibited by laws of physics; not available in some states of matter.)

(* If the actual number is less, then I'm sorry life has treated you like that. Truly. Fully-repairable bodies when.)