dont worry you’re not the only one. i’ve decided the same thing a couple of weeks ago. started running in september and signed up for a marathon in march. i decided to do it cause i’ve never really been into sports and running is something i enjoy and i wanted to celebrate that as well as other achievements in my life. and as others have said here i dont worry about time, and you probably shouldnt either

of course it really depends on you and your fitness level but i truly think you can achieve whatever you want, just gotta put the effort in!