Use of co values in smoking cessation are described where an apparatus may be configured to encourage smoking cessation in a user. The apparatus may include a sampling unit which receives a sample breath and determines a level of exhaled carbon monoxide from the sample breath. The sampling unit may be programmed to initiate a first timer for tracking a cumulative time upon a determination that the level of exhaled carbon monoxide is below a predetermined threshold. The sampling unit may also be programmed to initiate a second timer for tracking a countdown time upon a determination that the level of exhaled carbon monoxide is above the predetermined threshold, wherein the countdown time corresponds to a second length of time until the carbon monoxide level within the body of the user is expected to dissipate below the predetermined threshold.