Balancing Divine Sevice with Chizuk

Anonymous commented on "Cry to Hashem!" "What if you can't cry like that?
What if trying to do that makes you sick, so you can't do it?

what if trying or even attempting that makes your head hurt terribly, makes your stomach sick and you cannot go to work as a result?

what the heck are you supposed to do then?

this seems very unfair.

Excellent question! The answer is: If you can't then don't. Do what you can and yearn for more, while working on being happy with what you have.
One who does his or her utmost to fulfill a mitzvah and doesn't manage it for reasons beyond his control is considered to have fulfilled the mitzvah to the hilt.
Regarding children there is a very inspiring Midrash: When a childless person who yearned for children with all his or her heart leaves this world he or she will be very surprised to be presented with many children of his or her own in the hereafter.
"But I didn't have any children," he will stammer.
"These are yours since those who had them didn't really want them; the only reason they came into being was through your yearning and prayers."
Although progress is important it must be step by step. In the meanwhile we must avoid feelings that we are invalidated because we don't see how every prayer and mitzvah is another step towards reaching our goals. We must internalize that yearning and hoping to Hashem on whatever level we can --without overdoing it or getting sick from it--is in and of itself is more precious to Hashem than we can possibly imagine.
Rebbe Nachman said that even one moment of the struggle each person endures trying to come closer to Hashem on his own level is more precious to Hashem than a thousand years of an angel's impeccable divine service. The reason for this is simple. Because angle has nothing preventing him from serving Hashem his service is effortless and virtually worthless.
It follows that the more challenged one is, the more precious any little bit of spiritual movement is. A person with every advantage who seems more spiritually advanced may be on a much lower level than another person with greater challenges. Even if the more challenged person does much less, he is still higher.
Rav Nosson of Breslov explains that ethical works which make people feel depressed were not written to cause feelings of despair. On the contrary, their author's purpose was to give one a feeling that every tiny movement of spiritual advancement priceless and to encourage one to never pass up even the smallest opportunity for spiritual advancement.
If one finds that such works cause him despair he should not learn them since they are above one's ability for the moment. Instead one should fight feelings of despair by focusing on the positive and working to internalize that every little bit of good is very precious.
Eventually when one has amassed enough chizuk he can go back to concepts that were above him and slowly apply them to his life. Until that time, one must yearn to change for the better while never allowing this to overwhelm or cause depression. How to do this will have to wait for a later post b'ezras Hashem.