This study used a within-subjects design to assess the effect of three common cellular telephone (cell phone) functions (texting, talking, listening to music) on planned exercise. Forty-four young adults (n = 33 females, 21.8 ± 1.3 years) each participated in four, separate, 30-minute exercise conditions on a treadmill in a random order. During each condition, the treadmill speed display was covered and grade was fixed at zero. However, participants were able to alter treadmill speed as desired. Throughout the texting and talking conditions, research personnel used a pre-determined script to simulate cell phone conversations. During the music condition, participants used their cell phone to listen to music of their choice. Finally, participants completed a control condition with no cell phone access. For each condition, average treadmill speed, heart rate and liking (via visual analog scale) were assessed. Treadmill speed (3.4 ± 1.3 miles∙hour(-1)), heart rate (122.3 ± 24.3 beats∙min(-1)) and liking (7.5 ± 1.5 cm) in the music condition were significantly (p ≤ 0.014) greater than all other conditions. Treadmill speed in the control condition (3.1 ± 1.2 miles∙hour(-1)) was significantly (p = 0.04) greater than both texting and talking (2.8 ± 1.1 miles∙hour(-1) each). Heart rate during the control condition (115.4 ± 22.8 beats∙min(-1)) was significantly (p = 0.04) greater than texting (109.9 ± 16.4 beats∙min(-1)) but not talking (112.6 ± 16.1 beats∙min(-1)). Finally, liking during the talking condition (5.4 ± 2.2 cm) was greater (p = 0.05) than the control (4.3 ± 2.2 cm) but not the texting (5.1 ± 2.2 cm) conditions. In conclusion, using a cell phone for listening to music can increase the intensity (speed and heart rate) and liking of a bout of treadmill exercise. However, other common cell phone uses (texting and talking) can interfere with treadmill exercise and reduce intensity.