Medrash Rabba Bamidbor (12:3) / Tanchumah Nosso (11) Rabbi Yehudah bar Simon said in the name of Rabbi Yochanan, “This is one of the three commands which Moshe heard from the mouth of the Almighty and which took him aback: When He said to him (Shemos 30:12), ‘Each shall give a ransom for his life.’ Moshe said, ‘Who can give a ransom for his life? It is written (Iyov 2:4), “Skin for skin; all that one has [he will give for his life],” and still it is not enough. Thus it is stated (Tehilim 49:8), “Surely no one will redeem a brother nor give a ransom for him to G-d.”’ HaKodosh Boruch Hu, said to him, ‘I am not asking [a ransom] in accordance with My means but in accordance with their means.’ [Hence,] (Shemos 30:13) ‘This shall they give.’”
There is a statement made by Reb Zushya from Hanipoli of the two saintly brothers: When I go to heaven after 120 years, they won’t ask me why I was not like my brother Reb Elimielech but they will ask me why I was not like Reb Zushya could have been. Each person is expected to be the very best of his ability. Not that he will be compared to anybody else.
Given the second half: Summary: The deeper intention in the giving of the half a Shekel which is ten Geirah is that the person shall serve HaShem with all of his ten faculties. The reason why the Possuk gives the value of the whole Shekel as twenty Geirah is because when a person invests his half including all of his ten faculties to serve HaShem he is given a second half Shekel and now he has together twenty Geirah.
The Possuk: Tehilim (100:2) עִּבְּדוּ אֶת ה׳ בְּשִּמְּחָּׂה בֹאוּ לְּפָּׂנָּׂיו בִּרְּ נָּׂנָּׂה “Serve HaShem with joy, come before Him with praise”.
