Paradoxically, the perfect time to acquire Torah and good deeds is when one’s evil inclination seems to be at its strongest.
When everything is most volatile, that is the time in which one can ascend in spirituality and intimacy with God.
If one does not exploit the natural energy that one has when young in order to run, then when he is older it will become much more difficult for him.
If one wants to engage in the service of God, and this does not cause him to reach for the heavens, then perhaps he is not truly as young as he appears.
If a person does not desire great things at a time in his life when he is naturally driven toward them, when will he desire them?
Later in life, when a person declines, it becomes much more difficult to leap to great heights.
–Rabbi Adin Steinsaltz
From Talks on the Parasha