Mathf.MoveTowards
static function MoveTowards(current: float, target: float, maxDelta: float): float;
Parameters

current The current value.
target The value to move towards.
maxDelta The maximum change that should be applied to the value.
Description

Moves a value current towards target.

This is essentially the same as Mathf.Lerp but instead the function will ensure that the speed never exceeds maxDelta. Negative values of maxDelta pushes the value away from target.
var currStrength: float;
var maxStrength: float;
var recoveryRate: float;

function Update() { currStrength = Mathf.MoveTowards(currStrength, maxStrength, recoveryRate * Time.deltaTime); }