Hiya Paula,
I don't know a lot about life and about how the world works, but I do know that what is often described as the "law of attraction" is as real, unforgiving and non-negotiable as the law of gravity or the principles of electricity. If I fall off my chair, I know that I'm headed straight for the floor. Gravity is simple and straight forward that way.
Attraction is equally simple and straight forward. In my own life I've discovered that whenever I choose to focus on anything that depresses me and makes me feel blue, I become a magnet for more reasons and excuses to inspire and encourage depression and blues. Seriously though, it isn't necessarily that my focus on depressing thoughts makes everything around me depressing in its very nature, but rather, if there is any reason to be depressed in my environment, I am sure to notice it and latch onto it if I'm already in a depressed state of mind; it can easily become a habit to see the worst in people, life, and everything around us.
If on the other hand I choose to focus on things that feel like appreciation, laughter, gratitude, and forgiveness, same as with depression, I suddenly find myself noticing more and more reasons and excuses to feel appreciation, laughter, gratitude, etc.
Just like when I fall out of my chair, I will certainly hit the floor UNLESS an opposing force acts against the pull of gravity, the same is true of sadness and depression. Depressing thoughts will beget more depressing thoughts making them bigger and deeper unless and until an opposing force actively shifts the focus into a better feeling direction.
Honestly, for me, I gave up on any notion of a "therapeutic" component to sadness and depression a long time ago. I am way too susceptible to self-destructive thoughts and feelings to allow myself to go there. I make a point every day of writing down lists of things I feel grateful for; I write lists of positive aspects about my life and about people, things and situations in my life; and I make lists every day of things I feel appreciation for. And because my spouse turns up in those lists a lot, I leave them on the dining table for her to read every morning. I've been doing this pretty much every day for nearly 7 years now.
Not to say that I don't enjoy an occasional beloved sad song that makes me melancholy for a moment from time to time. I love music dearly, and I have had WAY more than my fair share of sadness in this lifetime. But when that sadness visits me (or anger, or hatred, or shame, etc.), I acknowledge it, honor that aspect of who I am and who I was, and then I go write a list of things that I feel grateful for (or I actively, consciously think about things that I feel appreciation for one after another.) And before I know it, I've turned my sad mood around and created a lighter, happier mood.
This just works for me. I feel better when my thoughts are mostly positive. Others enjoy being around me more (including my spouse) when my thoughts are mostly positive. And don't even get me started on the health benefits of positive emotions versus the health risks of negative emotions.
As far as I can tell, when I feel better, my life goes better. I don't have much control over a whole lot that goes on in my life, but I do have absolute control over the thoughts that I think. It has taken some effort, but it has been a huge benefit in my life to train myself to focus on better feeling thoughts as much as I possibly can.
Sorry this is so long; I guess I'm just passionate about this subject. I hope I helped rather irritated you.
Much Hugs!
Miharu