Now vs. Then

cyork10

I just started the c25k program on Saturday and as I was running last night I started thinking, three years ago I was training for a half marathon and now I'm contemplating repeating week 1 of c25k because I don't know that I can handle week 2 yet. So my question is does anyone have any suggestions as to how to deal with the mental aspect of not being able to physically do now what you were capable of doing in the past? I know this has been a huge struggle for me and I end up injuring myself from pushing myself too hard, too fast while trying to get back into shape.