Is being healed more difficult today than it was 50 or even 25 years ago? The only defensible answer is no. The Principle upon which healing is based is as absolute, omnipotent, and omnipresent today as 50 years ago, just as 3+4=7 is as demonstrable today as it was in 1950.
What may seem to make it harder to achieve a healing today is that the world is far more mired in materialism, medical practice, and depravity than then. Our mental castles are besieged day and night by an army of these aggressive and subtle influences. Even casual conversation and the nightly news have become thickets of stories and pictures of disease, sex, and depravity. It is the great red dragon become even more swollen by its evil.
Mrs. Eddy referred in S&H to a time when the world manifested more of "tongues in trees, books in the running brooks,/Sermons in stones, and good in everything". The mental climate of our time is certainly not spiritual, and one can easily become mesmerized and stupefied by contemporary aggressive evils if his mental watchtowers are not faithfully manned and his defenses are not vigorously maintained.
In short, the aggressiveness, ubiquity, and tenacity of mortal mind's claims today doubtless demand a more absolute, resolute, and energetic mental stance than in less materialistic times. Nevertheless, none of this has diminished by one iota Truth, Life, and Love's availability and power to heal every moment.