You need the motivation to meet someone else. The Portland Marathon offers free bimonthly training runs with 10 pace groups. When you need a rest day, take a rest day. A schedule is never something you can't change. It's just as important as your training days.
Some runners fear they'll sacrifice endurance if they take rest days.
On the big day, don't change a thing. And when it gets hard, and it always seems to at some point, that's what you've come to earn. That's the part that makes you a marathoner. It's not so much fighting through it as accepting it, trying to stay relaxed and focused. You'll get through it.