As we heal others we heal ourselves, and as we heal ourselves we heal others.
"I will heal as I let Him teach me to heal" - ACIM
Just as teaching and learning are the same thing, so does healing apply both to who you think of as a separate you, and who you think of as not you. Healing is the joining of the two into one.
So if we believe in sickness, that sickness is real or that it is really happening, or that there is truth to it, or that it is founded on evidence or real causes that pretend to be the reasons why it is happening, then we must be believing that we also ourselves are sick.
We cannot believe on the one hand that we are not sick while others are sick. Or that sickness is happening to them and not to us. If we believe in sickness, we believe in it period, and it applies everywhere.
This is why we have a vested interest, a shared interest, in bringing healing miracles to others, because as ACIM says, miracles help both the giver and the receiver.
We have to recognize that it is the ego's thought system of separation which convinces us we are not the one who is associated with sickness, and that it is someone else who is separately sick. Or that their sickness somehow belongs only to them and that therefore we want to keep our distance unless it infects us.
Perhaps the person is sick because we believe we are separate from them, and separation is the cause of sickness.
And if they are sick, and if it appears that we are not sick, we still must be sick because in some way we still believe that sickness is real. Only if we are able to overlook sickness in others and recognize their true nature, can we recognize our own true nature.
So either way, we must learn not to be deceived by appearances of sickness in ourselves or in others, equally, and to look past suffering to the truth of causality, cancelling out all of the artificial fake causes which masquerade as reasons why the sickness must exist.
There is no truth other than the truth of God, and in God's reality there can be no sickness. There is no separation. There is only eternal life. All other belief systems of "real sickness" are therefore artificial and untrue. All reactions to real sickness are therefore unfounded. And a failure to extend the truth and thus heal is simply evidence of our own current unwillingness to be healed also.
As you take steps on this healing journey, you will be included in the healing. It is the privilege of the forgiven to forgive, which means, those who have come to accept the atonement for themselves and thus are in a forgiving attitude of Holiness, are also now sharing that healing power with others and are now privileged to resurrect their brothers. To bring all back to the eternal life.
My healing is your healing. Your healing is my healing. We are one.