An anchor includes (a) an anchor head; and (b) a tissue-engaging member extending distally away from the anchor head until a distal tip of the tissue-engaging member, and configured to anchor the anchor to tissue. An anchor driver can include (a) a longitudinal shaft, having a flexible distal portion and a distal end; (b) a deployment element at the distal end of the shaft, reversibly lockable to the anchor head, and reversibly movable between (i) a locked state that retains locking between the deployment element and the anchor head, and (ii) an unlocked state that unlocks the deployment element from the anchor head; and (c) a tissue-piercing lance, reversibly movable between (i) an extended state in which the lance extends distally from the shaft past the distal tip of the anchor, and retains the deployment element in the locked state, and (ii) a retracted state in which the deployment element automatically moves into the unlocked state.