Running a marathon is a big challenge. While running 26.2 miles is the part you are given a number and (hopefully) a medal for, getting through the weeks of training and just making it to the start line is a huge challenge in itself.
If you want to stand on the start line of your marathon feeling as prepared as you can be, you’ll need to commit to a few months of consistent training. This doesn’t mean training every day, but it does mean finding a plan that is sustainable for you and sticking to it.