While your optimism is very endearing, this is not a decision for the person suffering from this particular mental illness and as a result shouting at them to care about things and do things is only going to cause that person more grief due to the supposed selfishness of their actions. Depression actually produces neuro-chemical imbalances and so requires treatment by a healthcare professional in order to correct said imbalances. This causes deficits in energy levels, concentration, pleasure gained from normally enjoyable activities like sex and music, just to name a few. If you are frustrated with someone close to you who is depressed the best thing to do is distract them, get them out of the house and doing things that they usually enjoy. This is will give you the desired results as opposed to telling them to go off by themselves, as the more time spent alone, the higher chance there is of that person killing themselves or doing serious damage. So, yes, go have your adventure, but do it with a friend or family member. This way you can ensure that they have company and won't do anything really stupid.