Christianity is itself about acquiring a spirit of mortification and self denials so that we both do penance, suffer with Christ and acquire merit, and achieve victory over the body and the passions.
You can buy an air conditioner. You can be comfortable. But you should be able to abstain at times from many things and undergo their opposites. Each person is suited to different mortifications.
I understand why people feel hesitant and tenative… afraid… it’s understandable… yet…
You shouldn’t be weak minded about it, nor find them upsetting. It is a joy to bear the cross. Christianity is not about embracing comforts of home, it’s about the cross and the joy of it.
Our happiness is not in this life, it is in the next.
Some people only have to do the smallest mortifications… others do more…
My general thought of possibilities for a beginner in mortification is simply eat things you do not like to eat, instead hate, wear perhaps a shirt that is coarser than you like, and be like the sinner striking his breast, saying, "Lord have mercy’ only strike a little harder till there’s pain so you wake up your heart to bear its sufferings with Christ.
We Catholics are not so effeminate as to not realize that there is great good in overcoming our desire to live always comfortably and painlessly.
Opus Dei I believe still uses the cilice.
If God calls you to greater mortification you should remember the examples of the saints – but remember also always to do it with a proper spirit.
God is not against physical pain for the sake of the kingdom, the very opposite, through penance we can uplift the world.

Worldly people run away from this, and give us worldly wisdom about how we should never do anything painful or act as if beginners will suddenly take on what the saints did… Certainly we must be sensible and prudent, but not in a worldly way which fears all discomfort.
Boxers go into the ring, and come out and have to recuperate for a month… Runners strain themselves to exhaustion, suffering sprains and bruises… People in the world endure all kinds of pains and difficulties and risks for worldly pleasures and causes… but suggest doing it for God?
What then do you hear?
‘You must practice, at one and the same time, interior and exterior mortification; but with this difference, that you must give yourself up to the first
particularly, always, and without exception; to the second, on the contrary, only as far as circumstances and the particular condition of persons and occasions will permit.’
St. Ignatius of Loyola
‘Oh, how I like those little mortifications that are seen by nobody, such as rising a quarter of an hour sooner, rising for a little while in the night to pray!’
St. Jean Marie Baptiste Vianney, the Cure of Ars
‘The reason for which it is necessary for the soul, in order to attain to Divine union with God, to pass through this dark night of mortification of the desires and denial of pleasures in all things, is because all the affections which it has for creatures are pure darkness in the eyes of God, and, when the soul is clothed in these affections, it has no capacity for being enlightened and possessed by the pure and simple light of God, if it first cast them not from it; for light cannot agree with darkness; since, as Saint John says: Tenebroe eam non comprehenderunt. That is: The darkness could not receive the light.’
St. John of the Cross
‘By denying our self-love and our inclinations in little things, we gradually acquire mortification and victory over ourselves.’
‘It often happens that when we take less care of our body, we have better health than when we bestow upon it too much care.’
St. Teresa of Jesus
‘That great saint, St. Charles Borromeo, had in his apartment a fine cardinal’s bed, which everybody saw; but, besides that, there was one which nobody could see, made of bundles of wood; and that was the one he made use of. He never warmed himself; when people came to see him, they remarked that he placed himself so as not to feel the fire. That is what the saints were like. They lived for heaven and not for earth: they were all heavenly; and as for us, we are all earthly.’
St. Jean Marie Baptiste Vianney, the Cure of Ars