You can beat the gloomies by creating an outdoor space complete with lovely outdoor furniture. A table and some comfortable chairs will beckon the most reluctant person outside and encourage you to stay there for just a bit longer. If you like gardening, perhaps you could do some while you are outside and that would be one good way to get some much-needed exercise.
There are many reasons for people to suffer from depression. Sometimes there is the need for prescription medication, but not always. It is possible to beat some kinds of depression by changing your lifestyle. Spending time outside in the fresh air and sunshine can be a good antidote to some types of depression, especially SAD. But some SAD sufferers live in areas where there is no sunshine for weeks or months on end, which is why they suffer from this form of depression.
However, for people who just feel a bit gloomy or irritable, going outside for a while can be really helpful. It seems to be because of the change of pace and environment. You have more space when outside instead of being enclosed in a small space, often with many other people. Just being out in fresh air and sunshine makes you feel good. If you can participate in some kind of exercise it is even better.