At the direction of my counselor, I once came up with a list of negative thoughts I had repeatedly (I'm not good enough, no one likes me, I'm too lazy...etc.) and I put each one of these to the test by asking, "What is the evidence for this?"
By asking that and realizing that in many cases, the negative thought wasn't EXACTLY true...it seems more believable than simply trying to convince yourself when you're feeling unloved that people do like me.
For example. A "bad" depressed thought process might be:

"I'm alone on Friday night. No one likes me, all my friends are sick of me and don't want to hang out with me. I'm a terrible person, I just turn people away because I'm so negative and depressed. Etc."


A "super positive" way to combat that might be:
I'm alone on Friday night. No one likes me...wait, that's not true! People do like me, I have friends!

Ok well I don't know about you, but that seems fake and unbelievable and wouldn't help me.

Instead, the idea is to be reasonable:
I'm alone on Friday night. No one likes me, all my friends are sick of me and don't want to hang out with me. I'm a terrible person, I just turn people away because I'm so negative and depressed. Etc. Ok, stop. What is the evidence for this? Well, I am alone. Why am I alone? Because Bill is at work, and he can't hang out. Mary is on a date. John is going out to the club, and I'm too tired for that. I haven't called anyone else. This is why I am alone, not because I am a terrible person. My friends haven't said anything to me about being sick of me, and I can ask them if I am concerned about our relationship. My depression is making me jump to conclusions about why I feel so lonely right now.

Not saying that I am the master of the "reasonable positive evidence response" thing. But I thought I'd try to explain...?