I have a few times. Only for a few months at most though. The process of quitting sucks. Even after tapering my consumption of the course of a few weeks, when the time to stop came I felt like a helpless wet noodle of a human being for about two weeks until things kind of normalized. It did make the workday exceptionally tough to get through at first, especially since I was in a customer facing role at the time.
On the upside, it actually made mornings far better in terms of my energy level surprisingly enough. A lot of the grogginess of waiting until you’ve had a cup of coffee before you can function in the morning disappears and you can just wake up and start your day. Losing the ritual of drinking a cup of coffee was bittersweet though and I had to find other ways to start my day off on my terms.
Seven months is plenty of time to train up to that distance if that’s your goal, but you’ll need to purposefully train if you don’t want to have a really bad time or hurt yourself. Your current fitness level and age will also be factors.
The main thing is that when you train for longer distances than your body is used to you need to slowly work up to the target distances so you don’t injure yourself. The general practice is the 10% rule where you should only ever increase your total weekly mileage by 10% from the previous week. As a former shin splint haver and person who ran a half marathon last weekend, running injuries suck and take a really really long time to heal fully from. You don’t want that when you’re on a tight deadline, so best to be careful.
Generally when you’re training for distance you don’t want to do more than a single “long run” day per week so that you don’t strain your joints and bones too heavily. There’s a bunch of “couch to whatever distance” schedules out there that can give you a good schedule to start off with as a skeleton and, if you want, you can modify it for your body and timetable. Your long run is usually only ever going to be like 80% of the race distance max unless you’re doing a race trial(which you should do once or twice in the last month or two of training).
I don’t know how high altitude this is and I don’t know if your body is used to the altitude that the race is at or not, but if it’s not you’ll also need to know that the lower air oxygen concentrations of a high altitude race will hit you like a truck if you’re not ready for it. Just keep that in mind and it will make things much harder. If you don’t have access to the altitude your race will be at you’ll essentially need to train for a longer race than you’re actually doing.
Hills suck. Hill workouts suck, but they also make your legs super strong, strengthen your lungs, and get you in shape very quick. Try to incorporate them into your workouts every other week or so in the beginning until you can add runs with decent hills organically built into them. Hills are a part of cross country running and you’ve just got to learn to power through them.
Get used to waking up early. As your distances increase and your runs take longer, first thing early in the morning is usually the only time to organically and consistently fit an hour or two of running into a day for most working adults if you’ve got a normal day job type schedule. Otherwise you’ll just need to figure out what works for you.