People are misled by the Mishnah that says, “Don’t be like servants who serve their master for the sake of receiving a reward” (Pirkei Avos). That really means the reward should not be the only motivation.  Certainly a person should hope for a reward. When he puts a mezuzah on his door he should desire a reward for it. When he says Krias Shema or Shemoneh Esrei, he should desire a reward for his actions. ~ R’ Avigdor MillerZt”l