Updated Jan, 20th 2013
I'm 28. I'm in pretty decent shape (about to start month 3 of P90X). However, I know that soon time is going to want to take its toll on my body if I let it. My main theme is maintaining what I have and maybe tweaking it just a bit to get a little more lean muscle mass and maybe gain 5 or 6 pounds of lean tissue.
Finish P90X successfully.
Run a half-marathon in March.
Run a full marathon sometime before June.
Gain 5 pounds of lean muscle mass(current weight is about 128lbs.)
Keep going with P90X everyday. Got this far, no sense in stopping now.
Register for the half-marathon that is being held in my city on March 1st by this coming Friday.
When P90X is finished in February, replace some of the workout days with running (will keep doing some of the P90X workouts after I'm finished like Yoga and some of the resistance days).
Successfully complete the half and continue training for the full.
My high protein, low fat and sugar diet starts Tuesday, so that should help me with the 5 pounds.
I think my fitness goals are completely achievable. My only concern is a nagging runner's knee issue that could slow me down on the races, but I've rehabed it for plenty of time since the last injury and I've changed into minimalist shoes that are better for my knee issues so I think I should be good.