The Baal Shem Tov taught:
Before Ne'ilah [the fifth and final prayer on Yom Kippur] pace yourself by reciting the prayers in the Machzor [holiday prayer book] for [during the repetition of] Mincha without such great concentration, so that afterwards you can pray Ne'ilah [the crucial closing prayer] with great Deveikut [devotional concentration].

It is interesting to note in this connection that in the Lurianic contemplative practices for Yom Kippur, the period of the Mincha prayer is one of recapitulation, getting ready for the final surge of theurgic 'progress' to take place during the Ne'ilah prayer.

[See Pri Etz Hayim Shaar Yom haKippurim, end of chapter 1;
As translated with commentary from Sefer Baal Shem Tov by Rabbi Dr. Eliezer Shore for //]