What can I do to make the most out of this summer? What can I do to bring myself out of self-pity?

This is not the answer that you want to hear BUT Here is a chance to get a reputation as a great guy and someone who everyone likes. This will get you your next job and maybe give you a chance to do what you want to do. If someone says I worked with him last year and he was lazy or he complained a lot you might not get that job. Think about it.