The antonyms for the phrase "make tense" would be to relax, loosen up, or unwind. When we feel tense, it is often because we are worried, stressed or anxious. To loosen up or relax physically, can help to alleviate our mental stress. Relaxation techniques such as deep breathing exercises, yoga, meditation, or spending time in nature can all help to reduce the feeling of tension. Taking a break from work or social activities and doing something you enjoy can also help to relax, loosen up, and distract your mind from the stressors that are making you feel tense. It is essential to recognize the importance of relaxation to prevent burning out and maintain overall well-being.