Have a heart is an unlockable challenge in The Binding of Isaac, added in the Afterbirth DLC.
This page shows information as of the latest Repentance release.
To see latest up-to date information about this challenge for the new Repentance+ (Online Co-op) DLC, check this page instead.
Note: this list does not include characters' default starting items.
All Red Heart pickups (except Blended Hearts) are replaced with coin pickups respective to the heart's value.
Items that actively or passively heal Red Hearts will no longer do so, including HP up items.
The following is unlocked for completing the Have a heart challenge: Re-Lax + ???
Defeat Mom for the first time.