A strong mind is more important that a strong body when it comes to completing THOR. If you believe deep down that you have what it takes to trek through 5(ish)K worth of off-road insanity, then it can be done. Look into your heart. Then look into your heart’s heart. There, and only there, can an answer be found.
And remember, don’t be scared! Keep in mind that you participate at your own pace. Walk if you want. Skip if you feel the urge. If you’re in a group, go at your group’s pace. Come across an obstacle too challenging? Go around it. The course is designed to be competitive but fun for all.
Also, medical staff will be on site and on call in case something were to happen.