Here's my situation: I'm a creature of habit and I'm in a routine where I do 30 cardio & 30 min weights M-F at the gym. In reality, I make it about 4 mornings a week due to work and family commitments. At the gym, I mostly do eliptical as my cardio, but sometimes treadmill. I would like to run a half later this year and plan on doing my long runs outside on Sat morning. My question is: Can I train for a half within the parameters of my current fitness regime? I can flex in the way I've got my cardio\weights split up and I assume I'll have to work in some rest days but can I build up to a half distance only running any significant lengths once per week?
Routine/the same old things is bad for you in any workout routine!!! (It's better than not doing one). Running a half will required more running than it appears you are doing, my 1st full I only ran 4 days a week. Find a plan and see if you can do it, I am sure you can. Hal Higdon has some great free ones on line.
I second the vote for following a training plan. I'm using Hal Higdon't Novice Half plan; you'll probably have to give up the weights on some days in order to fit in your entire weekday training run, but the plan has only one long run per week.