Congrats!! My first marathon was "karmic" in my opinion as well..it was on my BDAY!!
So, to answer your question.....a marathon is going to be hard to do in one year. WHEN is it next year? is it next year in january (9 months away?) or next year in DECEMEBER (20 months away?) Big dif
Ok, back to my point. Optimally (OPTIMALLY) you should have approx one year of steady consistent running under your belt before you even start training for your marathon. Think of it as insurance against injury ( and no, i dont mean it guarantees no injury.....but it helps)..it takes TIME for your body to adapt to the stress running puts on your joints and muscular-skeletal system. Seriously......running 18 milers and logging 40 miles a week, or more, is not something your body does without some coaxing, and TIME.
On the other hand, if this is something you are committed to....
You CAN do a 10K or Half, if you WANT TO. you don't have to if you DON'T want to. Its a great way to progressively build up your miles, with smaller, closer more tangible goals along the way. You can train for a 10K in 8 weeks..... or less.....you can train for a half in 12...... and the great thing is that as you do so (if you did) you'd be building not ONLY your longest run distance (from 3.1 to 6.2 to 13.1) but more importantly (in my opinion) you'll be building your weekly base mileage. THIS is going to make or break your marathon training. How many miles a week do you run right now?
When i was peaking for my marathon in October i was pushing 70 miles a week... you dont NEED to be able to run that much... BUT you have to consider your "long run" that week of 20 miles...yes- i said 20 miles...plus at least another 20 during the week, and you'll be running about 40 miles, at peak training. at least

Probably
Back to task at hand.. you can start now, by increasing your weekly mileage. Dont worry about speed, dont worry TOO much about distance (ie, getting progressively longer runs)...just worry aout getting MORE RUNS in during the week...or more MILEAGE...however you want to do it. Start by adding one more day of running..than tack on a mile to one or two of those runs in another couple weeks...in a month or so add another day. Then start running long...whatever. But you want a good solid base of about 20-25 miles per week before you start the marathon program..... training for a 10K or half is a great way to have a built in way to ramp up your miles. Try Hal Higdon training plans...go to halhigdon.com he has great beginner programs for half marathons (and marathons!)..maybe 10Ks too...very gentle, and *fairly* low mileage.....
if you give me more details about your running currently i can help more!
oh, and congrats on C25K! are you going to run in a 5K race?
And congrats on the weight loss....

As you lose more weight youll find its easier to add mileage and go faster...but at 5' 8" you arent carrying around as *much* extra as i was initially thinking... unless the 86 is in STONES!!!!!
