Chinuch for Doing Mitzvos

I found it interesting to read that Rabbi Matisyahu Salomon, mashgiach in Lakewood, says that if a parent speaks to children about the advantages and rewards of doing mitzvos, rather than the joy of living with mitzvos, this is not a good idea (I found it interesting because so often you hear that the goal is Olam Haba).

He says that if you tell children, "Do this mitzva because if you do it, you will get a reward" or if the parent says excitedly that he himself is doing a mitzva in order to get Olam Haba, this is not good chinuch.

He explains that this only teaches children to do a mitzva because it is worth your while.  The child might think that for his parents, Olam Haba is wonderful, but he has other ideas about what makes something worthwhile.  He can think: Let my parents go after the reward that interests them and I will go after the reward that interests me.  He will have learned that mitzvos are done for the rewards and he can apply his own standards of rewards.

If, however, the child sees the joy that a parent has when doing a mitzva, if that joy is the foundation of the home in which he grows up, then, says R' Salomon, he will inevitably be affected by the spirit and the mood and the atmosphere and he himself will feel that joy when he does the mitzvos.  This kind of chinuch will reach him no matter what he thinks constitutes a worthwhile reward.

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What about being mechanech children to do mitzvos to bring Moshiach, to "make a brick for the Beis Ha'Mikdash?" Is that something that can motivate children and is it good chinuch?

If it's done as a "formula," something said by rote, then you shouldn't count on it motivating them.  But if you are able to convey to children, whether aged 3 or 6 or 10, how Moshiach's coming is something they personally want and it's immediate and real, then yes, it's good chinuch.