Anyway, don’t be discouraged! Your goal is absolutely doable! 如果你有跑步底子 (even just a little) you should be able to train and be ready ...
lvrunner thanks for your encouragement and advices. yes i'm trying to follow this Hal Higdon's Marathon Training, and it seems progressive and doable. I just started the training but it is truly a joyful experience to see myself improving.