One of the leading evidence-based interventions for depression is Behavioral Activation - a strategy designed to get people with depression doing something that provides some type of emotional "reward" (e.g., sense of accomplishment, pleasure, gratitude).
Traditionally, this involves having people assign 30 minutes per day as a "pleasant activity time" during which they choose from a menu of things that they either know they enjoy or used to enjoy. A great one can be found here. Simple right? For some people, yes, but not for others.
Some people are able to maintain motivation and energy despite their depression. However, many others are not. This lack of energy and motivation is often a symptom of depression, so depression inherently makes getting out and doing pleasant activities difficult.
I find that it can be extremely helpful to liken depression to a parasite or monster. By doing this, the person with depression (maybe you) can more easily imagine the fight you are having. Depression wants you to stay home, sleep, or avoid people. Meanwhile, you have to fight back by getting out and doing the things that depression does not want you to do. Only then will depression start to fall away.
You might find that this analogy gives you the extra push to get out the door. But what if it doesn't? Then, you're going to need more structure and support to engage in pleasant activities. Ask a friend or partner to come get you and take you to do something, make a commitment to a volunteer agency, post sticky notes around the house, set reminders on your phone - do whatever it takes to get out and do something that might insert a little more positive experience and emotion back into your day. With that, you hopefully will start to heal and win the fight against depression.