Exercising once a month will not do much to relieve stress. Some people find meditation helps them relax and handle stress. Try to rest and get enough sleep. This may be difficult, stress may keep you up at night, although, some people welcome sleep as an escape. The less sleep you get, the more stressful you will feel, and the higher your chance of becoming ill because your immune system will weaken.
Deep breathing can shake of stress affects and can be done anywhere.
Take a day off, that's what weekends are for. Take a drive, go to the beach, work in the yard, read a book. Hobbies are great for relieving stress. Take the time to enjoy what you like doing. Don't feel guilty for spending time and money doing something for yourself.