JJ's right.
Run more. Run longer too. If you enjoy HM's, and lots do, then I'd suggest making your regular long run 14 or 15 miles. That way the HM is a doddle. The midweek sessions look good with hills and "speed". Although I don't know whether the speed session is tempo (ie a 6 miler at a hearty push, just outside the comfort zone, say at HM pace), or whether it is an interval session (1 mile eyeballs out, 2 min rest, repeat repeat repeat. Add a mile warm up and warm down. A good session).
The hills and speed sessions are good for improving leg speed, but won't improve your endurance much. That's where running more miles at an easy pace will help.
Excuses:
1-I'm tired: You need a run, any run.
2-I ran hard yesterday: You need an easy run.
3-I ran last night, I've only got time this morning: Great, you need a run, see 1.
4-I ran this morning: Go onnnnn, you know you want to.