Writing from experience vs. making everything up

For the last couple of years, I have been writing a lot - however, it was not for myself, not on my own books or poetry. I did not even write any morning pages for over a year. My own creativity seems to have disappeared for the sake of earning money, for the sake of making a living, for the sake of being able to survive, for having a roof over my head and money that can buy food.

Yes, I write - but you won't find much under my own name. In the last two years, I wrote as a ghost-writer, I translated a lot of texts from English to German or the other way around (proper books, e-books, terms and conditions, brochures, websites, marketing documents and so on) and also wrote quite a few SEO texts for companies. It's not the kind of money that would allow me to live a really comfortable life and I don't see how I'll ever own my own house or a new computer - but I'm just getting by.

Getting by and being happy, however, are two different stories. I wish I could spend more time on writing my own things. I guess I could find the time but I feel like most of my writing energy is drained by the jobs I am doing every day and when I write on my own stories, the stories are usually quite dark and I often stop writing because I don't want my book to be a solely dark, shadowy story with depressed characters.

The problem is that I don't know much about happiness. It's hard for me to write about it and to make my characters experience wonderful things because every time I try it "sounds" artificial and made up - just like as it was written by someone who never made those experiences herself. That's the problem because that's me.

Just today, I came back into the house after doing some work outside and I was quite sad. There was no one to talk to (as usual) and the computer seemed the only solace. I thought I might as well write all my feelings out of me, put it on paper, let my characters be the ones with the problems. So I wrote a scene between two of the characters in my novel. One a major character, the one other only minor because she'll only stay for a few chapters. They have a conversation and I planned it to be a relief for both of them because they finally found someone who understood them even though they two women come from completely different backgrounds. However, now that I have gotten through the descriptions of their problems and to the stage where they would be quite happy in rejoicing about having found some understanding, I am stuck. I don't know how to move on, how to describe their relief and their happiness that they are slowly starting to show.

Do I simply lack the skill for story telling or do I lack the positive experiences in my life?
What is it like for you? What's easy for you and what is hard? Is it easier for you to write about things that you have experienced in one way or the other? With this, I don't mean that good crime writers and horror writers all need to go through thus gruesome experiences - I am talking about the world of feelings and emotions. How do you go about describing something that you don't have any or much experience with?

What keeps you writing? What gets you started?

I know that right now I should be using my time to work towards finishing the book I would like to publish but when I think about it, I feel demotivated. And I'm not sure why. I know that there are people out there who would be interested in reading the book and I kind of have the whole story in my head. I also don't have any problems with typing up things: as you see, I have just written this blog post. So why can't I get myself to write on the book? Maybe because parts of it make me sad? Maybe because I'm afraid that I wouldn't find a publisher?
Why do I even stick to writing?

If you are a writer: How do you get yourself writing?
What get's you started? Do you only write when you are motivated or do you force yourself to write?
How do you treat stories that need to be written but make you sad?