1). Depending on where you are in the world it’s hot as fuck right now. For me, this morning was miserable. I kept my pace easy, I took a couple breaks, but I hit my miles. Sometimes the summer is something that you survive and then enjoy the endurance gains in the fall.
2). What’s your typical volume? Is a 7-mile run more than 25% of your weekly volume? If it is, you might scale that back. Overall, for a new runner, the most important thing is building your weekly volume. And it should all be easy. Try to get to 35 comfortable miles a week before you add in workouts or anything else. These will help, but not nearly as much as just running more. Specificity is a thing, after all.
3). Do you like running? I’m not going to try and talk you out of something that I really enjoy, but sometimes I take a brain break and swim, or ride my bike. I usually come back pretty refreshed. If you’re just beat, maybe give that a shot?