I have a problem...I really love to run but have a couple of back issues and I can only one long run (maybe two if one is a short run) per week plus some cross training (spin and elliptical). I've been successful with 5ks and a little longer distances but really want to do a half marathon this November. Any ideas of a training program that will get me ready for this?
I agree with the advice for strength training...weights take awhile to produce results, but consistent work will make a difference. The other thing is try running in a tightly-fitted vest. (It can be lightweight, but needs to be snug and longer to secure slightly below the waistline). This helps a great deal with posture and aids in lower back support).
If you are looking for a specific training program, there are tons available on the Internet (many are similiar, cookie-cutter suggestions, so my humble advice is just to slowly increase your long-run schedule (do double miles on some days with mornings and evenings) and continue with the weekend races to include 8k and 10k opportunities.
Here is an example of a schedule http://www.runningthroughlife.com/wp-content/uploads/2012/01/Half-Marathon-16-Week-Training-Plan-Level-2-Beginner.pdf
Again, do not push yourself because you have plenty of time to build your endurance and work up to the distance.
Wishing you all the best!