After the Jew's sinned with the golden calf and did Teshuva they were shattered, so Moshe Rabenu lifted them up - (Ki Sisa) into a half a Shekel, which means that they became a complete vessel but an empty humble one.

More then that we have to be the 2 halves of a Shekel by 2 types of Avodah:

1. Milmatah Lemalah through Davening and doing Mitzvos.

2. Milmalah Lematah through learning Torah.