I assume you are speaking about the Super Suicide Society of the Summer Session meetings.  How Gene feels about these meetings is discussed early in Chapter 3.  At the beginning of each meeting, Finny and Gene must jump first, to set an example for the group.  Gene says, "I hated it. I never got inured to the jumping," and when he was ready to jump, "I felt a flash of disbelief that I was doing something so perilous" (34). A bit later Gene describes his feelings as he prepares to go to the meetings. He says it didn't occur to him to tell the truth, that in going, he was "acting against every instinct of my nature...(34).  So Gene's feelings seem pretty clear, don't they?  The more interesting question might be to ask why he continues to do something that he hates and fears so much!