Often, feelings of sadness, uneasiness, and loneliness are vague and unattached to specific events. This makes it more challenging to find ways to turn you mood around. When you find yourself in a funk, focus on what you're feeling.
Your real life is in the here and now. Once you figure out what kinds of experiences cause you to feel certain ways, you can change either the experiences, or when that's not possible, change your responses to them.