u/Entire-Rip-6549

I’m 17 days out from my first marathon and starting to lose confidence in my race goal (3h20m). Looking for perspectives from experienced runners. (All paces/distances are in min/km and km.)

Background:

• 48 years old, been running for 3 years.
• Background in soccer, but no endurance sports before this.
• Over the past 3 years, I’ve run several races.
• 3 weeks ago, I ran a half-marathon (as part of my training block) in 1h37m.

Training so far:
I’ve been hitting all my interval, tempo, threshold, and uphill workouts without issue.
However, I bonked hard on my two longest runs.

Run 1: 32 km

Goal: 26 km at 5:00/km pace
Reality:

• At km 17 and km 22, I had to stop completely to fuel/hydrate because I was out of energy – those kms were at a walk pace.
• Total achieved: 20 km at 5:00/km, 3 km at ~5:15/km, rest were at 6m30.

Run 2: 35 km

Planned structure: 16 km easy + 16 km at 4:40/km + 3 km easy
Reality:

• Managed 16km easy + 11 km at 4:40/km, then hit the wall.
• One slow km, then one more km at 4:40/km, then a major slowdown at km 30.
• The last 5 km were a shuffle just to get home.

Based on these two runs, I’m starting to doubt whether my goal pace is realistic.
Can anyone help me make sense of this? Am I overthinking it, or is this a serious red flag?