How often do you read things you wrote a few years ago?
I think it's a good way to chart your progress as a writer. You can look at an older work and see how much you've grown in terms of voice, style, character development, word choices, etc. You may be tempted to look at an older work and cringe. That's OK -- I've done my share of cringing. Just make sure you uncover your eyes long enough to notice that you've progressed as a writer since you wrote that cringe-inducing passage.
Sometimes, though, you might surprise yourself and uncover something you really like. This happened to me the other day. I was reading an older work and, yes, cringing at some of the things I wrote. Right after a passage that made me want to gouge out my eyes, however, was a bief dialogue exchange I would have been proud to write today. In addition to charting your progress as a writer, older works can show you that you had the talent years ago and have just spent the intervening time honing your craft.
At least that's what you can tell yourself when you're not cringing. . . .
Happy writing, and make sure you uncover your eyes and read the good parts of your old works, too.