Those chosen by GD to enjoy the treasures of the world to come will experience " a great bounty of indescribable good.., one should employ the mean to attain the high degree of pious worthy of this Divine grace"
pg 445
Nefesh Hachaim
The more you internalize the lessons we have covered so far, guiding you to clearer thinking and pure intention the more your service of H'shem in the areas of learning Torah, Mitzvot, and Yirat Shamayhim will develop the purity of intentions as well
Prologue to Gae Four Chapter 1 pg 119