I suppose I should warn you about something. Something I wish I had been warned about before I started racing. I think there is actually a technical name for it out in the racing world, something like "The Post-Race Blues" and it is a very real thing.
It's so weird. You train for months and months to achieve this incredible goal. Sometimes you dread it. Sometimes you love it. Sometimes you just do it to get to that end goal. Race day comes and it's incredible. The energy in the air and the excitement and anticipation all combine to make you feel like you want to pop. You've been waiting for this day! You race. You cross the finish line. You feel awesome....and then, wait, what's that you're feeling? Kinda crappy. Is it depressed? Is it lost? Whatever it is, it's not a good feeling.
So what happened? Well, what happened is totally normal and expected. You've worked really hard for something. It's been built up for a long time and you've accomplished it so naturally you feel a little lost without this goal you've had your sites set on for so long. That's okay. It's normal, even among the top athletes of this world. Even among non-athletes--anyone who has accomplished any great feat feels this drop. All you need to know is that it's very likely coming and you'll need to face it.
So how do you face it? With a plan of course. Just knowing that it might come is very helpful. That way you won't feel bad or worried that something is wrong with you. But going one step further and having a post race plan is even better. Humans do better with purpose. What do you want to accomplish next? Have a list of things you want to do, they don't even have to be race related, and when your race is over set about accomplishing the next thing on your list.
Then remember, the joy really is in the journey so enjoy every step.