a stupid runner without running pants

I went to Sento for Yoyogi Park Run on Wednesday night, then I was too late, time was past 8 pm. Park running group might have finished over half distance of total mileage. But I decided to run alone even they could return to Sento earlier than me.
Therefore, how can I manage 18K park running without running pants? If I asked cheeky Gareth, he would be laugh "huhuhu..." but that's impossible... it's kind of naked.

I begged Steve to reschedule running plan, I didn't want him to disappoint me since I was Obaka-chan; forgot to bring some stuffs. By the way, Obaka-chan means stupid person.

So I asked him and he had no alternative and could rescheduled that.
I have decided to replace my schedule to Thursday's plan with Wednesday's plan.

On Thursday late afternoon, went to Gosho for 3.3K warmup, and next moved to Meiji Jingu Picture Garelly for pace run at 4:40. Jayne could company me even she had a hard run on Wednesday' night and Thursday morning. Actually, Jayne is getting improved her running, so amazing.
After warming up at Gosho, did pace running for 11K. In the beginning, I follwed to run at 4:40 pace, but I got slow down to around 5:00 after 6 laps, my legs were so tired, couldn't move.
In the middle, when I was at good rhythm, my very expensive Polar watch has stopped even I was measuring my mileage and all log, so much disappointed... and then lost my motivcation so just ran as easy and slow after 6laps.

wednesday: no choice without taking a break.

thursday's efforts:
mileage: 18K
Gosho for warming up for 3.3km, 1,325m*10laps(6 laps at 4:40 + 4 laps easy) + moved to Gym.
time: about 1h40m
begining time: 7:40pm

friday's efforts:
mileage: 3.5K
venue: zenpukuji-park, suginami
time: 19m51s8
avgHR: 132-68%
avg Speed: 10.8km
calories: 140kcal
beginning time: 10:06pm

weekly mileage: 36km