It is quite easy You can get a bunch ideas from FlyerTalk.com.
Do a search of the AAdvantage forum for something like "expiring miles"
From time to time AA will run sweepstakes and other promos that can earn you a few miles just for signing up. You can get info on facebook https://www.facebook.com/aadvantage or https://www.facebook.com/aa
The Summer Miles Challenge will give you 100 miles just for signing up.
https://www.facebook.com/aadvantage/app_292705677490552
Any activity, in or out will extend the miles.
The Dining idea is a good one. I rarely look for a restaurant that gives miles, but pick up a few by chance.
If you absolutely can't find something to do, then for a few hundred miles you can get a magazine subscription. You can also donate miles to soldiers or kids, either online or by calling AA. http://www.aa.com/i18n/AAdvantage/re.../charities.jsp