D&C 24

Being the first two elders of the Church, the Lord provided instructions concerning the administration of priesthood blessings saying -

"Require not miracles, except I shall command you, except casting out devils, healing the sick, and against poisonous serpents, and against deadly poisons;
14 And these things ye shall not do, except it be required of you by them who desire it, that the scriptures might be fulfilled; for ye shall do according to that which is written."  (Doctrine and Covenants  Section 24:13 - 14)

Speaking of  "healing the sick" the Lord instructs that "these things ye shall not do, except it be required of you by them who desire it".  I've thought much on this instruction.  I understand that James instructed much the same asking -

"Is any sick among you? let him call for the elders of the church; and let them pray over him, anointing him with oil in the name of the Lord:
15 And the prayer of faith shall save the sick, and the Lord shall raise him up; and if he have committed sins, they shall be forgiven him."   (New Testament  James 5:14 - 15)

Again, the instruction is that he that is sick should call for the elders of the Church.  Obviously, it is because their is a requirement of prayer of faith.  I understand the current Handbook of Instruction instructs -

"Melchizedek Priesthood holders who visit hospitals should not solicit opportunities to administer to the sick."

Again supporting the idea that "except it be required of you by them who desire it".  But the Lord provided the condition of "except I shall command".  I personally believe as we visit the homes of the ill and the poor and needy, when moved upon by the Holy Ghost, sensing such desire and faith, it may not necessarily be inappropriate to ask if one would desire a blessing.  I have experienced sensing that desire, where upon asking an individual, that individual broke into tears hoping that I would be willing to do so.  The desire was not necessarily looking for a miracle but a desire to be comforted.

I believe the real purpose of this instruction to not solicit to give blessings is more related to the intent of giving the blessing as is it more related to as desire to "Require...miracles".