This experimental study investigated whether affective states influence physical strength. A sample of 32 university students participated in two interventions and one control condition. The interventions were a time-constrained puzzle and a guided, anger focused visualisation. After each intervention and during the control, participants tested their grip strength with a hand dynamometer and estimated eight different affective states through continuum-scales. Participants were the strongest during the control, being statistically weaker during the puzzle intervention compared to control. Both interventions induced multiple affective states, including anger. A simple linear regression gave a statistically significant model where 13% of the variation in grip strength difference, between the puzzle intervention and control, could be explained by the difference in anger between the same trials. Participants’ difference in grip strength between the trials could be predicted as -5.08 + 0.09. For each value that the puzzle intervention rated higher in anger, grip strength was increased by 0.09 kg compared to the control. The model showed a positive moderate correlation. Higher anger during the puzzle intervention increased strength output relative to the control, despite showing a lower mean grip strength. Anger, under the proper circumstances, appear to increase strength output, but more research is needed.