Like I said, what you described can help. And you did give potentially good advice. But you're presenting it in a way that is going to turn a lot of people away.
Also, there are a lot of people who have dealt with this for years (myself included) and "distractions" don't really help. I personally don't want a distraction.. I want to work toward living normally. Unfortunately, going out and enjoying nature and people isn't easy for many, and it often doesn't solve the problem. Some people aren't ready for social activity either, and trying to force it too soon can make things worse.
I'm sorry, I'm not trying to make you feel like a jerk. Like I said, your heart is in the right place. And maybe you also have Depression (it's certainly possible) and this helps you. But if you're continuing to have episodes over the years at the same rate you always have, then maybe you should do more than just going outside?
For me personally, social activity is a type of preventative treatment. I have to be out of the house X amount of time or else I slip. But if I do slip, going outside isn't going to help anything. I have to solve things in other ways. Like you said, everyone thinks differently and that's why there's no magic cure-all.
So the best advice I can give here is that we should be seeing professionals who have more knowledge than we could hope too. Depression is a mental illness. If our brain doesn't work right, why should we trust it that it knows how to fix itself when it's been broken for so long? That's how I think about it anyway.
It's certainly possible to live without professional help. So I can only speak for myself here. But for me, the only time I truly started getting better was when I went to therapy regularly. In fact I still do go to therapy even now. It is just not as often as it used to be.
Sorry for the wall of text. I hope you are able to help yourself and others. Just use this as a learning experience that how you word things matters. We should be taking very careful approaches to addressing people who are dealing with these issues.