What do real labor contractions feel like?

I'm a FTM and not good with handling intense pain. I'm due in December and I keep getting so nervous just thinking about giving birth. In your opinion, does it hurt worse pushing or do the contractions hurt worse? Do the contractions just start randomly one day at the maximum, or do they slowly build up and get worse and worse? I plan on getting an epidural but Im still curious in case it doesn't work D: