The Mishnah states "L'fum Tzara Agra"- the reward is in proportion to the exertion (Avos 5:23):
בֶּן הֵא הֵא אוֹמֵר, לְפוּם צַעֲרָא אַגְרָא:
Ben He He said: According to the labor is the reward.
This applies to matters of spirituality and also to 'afterlife'. My question is then, if someone faces very few challenges in life (and they themselves personally feel that they faced very few challenges), would this mean that they would receive fewer rewards in the 'afterlife' even though they just lived normally and naturally didn't happen to face any troubles in their worldly life? Would it mean that they'd get fewer rewards because their life wasn't difficult and they didn't go out of their way to make it so?