Praying to remove suffering is problematic

 Nefesh HaChaim (2:11): Even though it is a clear halacha in the gemora that an individual can add requests in prayer for his personal needs and suffering in each beracha according to the subject, it still should not be done because of his concern for his personal suffering. That is not the correct approach for those who are truly righteous. It is truly puzzling how it is possible to ask anything at all from G d so that his suffering should be removed. The issue is analogous to being cured from sickness. The doctor gives him strong medicine or in extreme cases amputates a limb in order to prevent the spread of the poison causing the illness. Does a person beg the doctor not to give the medicine or not to amputate the limb? The sick person is in fact paying to give him these unpleasant treatments. Therefore, one should not pray to have suffering removed. They are in fact the ointments and medicines that revitalize to atone for sin. Our sages (Shabbos 55a) stated: “There is no suffering unless caused by sin” - because the sinful person cannot obtain atonement without suffering.