If you have any slight desire to have your baby without drugs, you should know something very important: the pain of contractions peaks at around 7-8 centimeters.
Of course this may vary slightly from labor to labor, but for most women, the pain will not intensify after you have reached that point. In transition (the name given to the last couple centimeters of dilation), the contractions will most likely become closer together, but their strength will not increase.
Make sure your husband, doula, or birth partner knows this and can remind you of it when things get intense in labor. Use that fact to help you determine if you truly can't take it any more and need a break, or if you have come far enough that you feel you can muster the courage to finish.