Here I am a 50 year old male, been running consistently for recreation and fitness since forever, 8 months ago started running in formal events (New York Road Runners) and found that I loved it so much I just had to get serious. Finished a couple 1/2 marathons with no serious difficulty, first at a 9:00/mile pace in January, then in May at 8:25/mile. A couple weeks ago I succumbed to the temptation to sign up for the Philadelphia Marathon on 23-Nov-2008.

I have been training sort of informally, 30+ miles per week, one 12 to 14 mile run per week and climbing, but I realize I am behind schedule on adopting a real program. So, a little Internet research and I find plenty of free generic programs (intermediate, advanced, etc) and a site -- runningplanet.com -- that offers non-free, specific goal-time--targeted programs. The latter is tempting me, and in any case I need to establish a time goal. By the "best 1/2 marathon time times two plus 10 minute" formula, I would shoot for 3:44. I think because of my age and inexperience in serious distance, I should be more conservative. The question I am  debating is, shoot for 3:50 or 4:00?

Any thoughts?

Thanks.

PS To those  who crawl around runners' forums all over the web:  forgive the cross-post.