Is it crazy to run your first Marathon at 40? Posted on May 1, 2014December 18, 2014 by Grace Lu 01 May Marly: Is it crazy to run your first Marathon at 40? I have run two half marathon’s, both right at 2:28. If it’s not crazy, what is a good training program? Post by Favorite Run. Any advice on how to start running? My left foot went numb when I wear my new running shoes, any suggestions?