Sefer Avodas Panim (written by Rav Aharon Yosef Luria zt”l) asks how we are able to derive enjoyment in this world. Doesn’t this deduct from the reward in the next world?
He answers with a moshol: A man who worked in a grocery store once made a deal with the owner. It was agreed upon that he took take anything he wanted from the store whenever he wanted. He would keep a record of what he took and it would be deducted from his pay at the end of the month. Of course, only things he took on credit were deducted from his salary. If he were to take something and pay for it right away, he wouldn’t have the amount deducted later.
So too, if a person gets pleasure from this world, it is deducted from the “payment” he would have received in Olam Haba. However, that is only true if he doesn’t “pay” immediately. If he pays right away, he is able to receive his full reward in the World to Come.
And how does one pay in this world? By making brachos and thanking Hashem for providing for him. For this reason, a bracha is referred to by Chazal as a “matbea” (coin, see Brachos 40B), as it is the currency used to “pay” Hashem.
We learn from this that more one thanks Hashem in this world, the more he will be able to enjoy his reward in Olam Haba. This idea can be used to explain the pasuk (Tehillim 116:12-13): “How can I repay Hashem for all His favors upon me? I shall lift up a cup of salvations, and I shall call out in the name of Hashem.” The way we pay Hashem is by praising and thanking Him.
