The של״ה הקודש points out that the three gifts that are acquired with יסורים, suffering, are alluded to in פרשת ואתחנן. They are the acquisition of Torah, Eretz Yisrael, and Olam Haba.
The study of Torah is emphasized by the commandment to learn Torah. This is derived by the words, ושננתם לבניך, and teach your children, taken from the Shema. How are we able to teach our children if we don't study ourselves?
Eretz Yisrael is mentioned by the commandment to destroy the seven nations. These seven nations represent the ultimate in impurity. Israel is meant to be a holy land which requires us to remove that which is not holy.
The concept of Olam Haba is hinted at whenever the word "טוב" is used. The real "good" that awaits the righteous is in the next world. This is why the Rabbis mention that one moment in Olam Haba is equal to all of the bliss one might have in his entire life.
These three precious gifts of Torah, Eretz Yisrael, and Olam Haba only come to us by way of hard work and diligence.