Write, write, write -- use your imagination
How do you become a better writer? By writing. It's the only way. I don't care who you are, or how truly crappy your writing is, if you'll allow yourself to write every day, your writing will improve every day.
If you don't like writing, and find it too hard to write every day, you need to rethink your approach. Some writers have a drive to write, but they're scared. Consider therapy. It can help.
Maybe you're just lazy. If that's the case, make a commitment to writing. Set a goal. Tell yourself that you will meet your goal, or give up all aspirations to write. You need to be disciplined.
On days when it's hard to write, IMAGINE yourself writing. Ignore every thought you have, and just picture yourself writing, sitting at the computer, or with a notebook on your knees in the garden, or talking into your digital notetaker... your imagination is much stronger than your will, so use it. :-)