Who are you, really? What are you responsible for, in any situation? Some people are unable to voluntarily move, except for their eyelids, by which they can communicate -- or some, not even that. What are they responsible for? Who are they? The connection there is "who you are is what you choose". Maybe that's an overly simplistic view of human nature, but I think it at least captures something important, and I tend to want to favor it.
We face limitations due to aging -- we may all face that, either now, or, if we survive, in our future. There are other limitations besides that, which occur with less universality. Are we defined by our limitations? It depends on what we mean by "we". I would say that the paralyzed person is not defined by their paralysis. If they were put in a different body somehow, they would physically act out their personality. The body is accidental, not essential. I can't hold a paralyzed person responsible for not moving -- maybe partially so if they knowingly chose to paralyze themself (a rare occurrence), but even then, they would no longer be able to change their minds after the fact, and would have to live with the decision of their past self, who increasingly would be becoming to them a separate person. Likewise, I can't hold myself 100% responsible for the body or life that I'm stuck with. To an extent, it's not me. Essentially, it's something stuck to me, and to a large extent, other things than my choices are responsible for it.
However, it is more true that the way that I approach life emotionally, with my inner eye, and with my inner will, and the way I choose to think, does express who I am. If I were completely paralyzed, but still myself and still conscious, how I thought about life, and paralysis, would be me, would be an exercise and expression of me being myself. The state of my heart in the present moment is a root responsibility that I am always capable of disposing of properly.
So in this space of minimal limitation, in the world of what I choose to think and how I choose to see, I can express and exercise my heart (the true preferences and intentions within me) by having courage. To approach whatever there is, and whatever limits me, without flippancy, arrogance, impatience, or despair, but rather with courage.
Forces like depression and anxiety can seem to be me, and I can feel, in despair, that they are more powerful than me, that I must bow to them. In a sense, perhaps I must. If I must bow to them, how can there be a God? My mind can shut down to the spiritual and intellectual world if I identify so totally with my limitations. I can live in a narrow world, made up of practical concerns and the desire for the luck or therapy for me to not be beset by my psychological problems. If I am so limited, in a world where the only relevant thing is my narrow well-being, and God is not admitted as a person who can address that narrow well-being, of course for me God does not exist. I might say that he exists, or halfway believe it, but on the level of trusting, I do not believe that he exists.
In some way, the sense that I am not myself in the face of mental forces connects with my inability to say "God exists". Perhaps because in order for me to believe in the existence of God, I need to believe in the existence of myself. Myself, a free-willed being, who sees things according to his own lights, and thus is able to see the intellectual and spiritual world, things which are true in themselves, apart from what is forced on me, things which I must find unbearable or attractive in the pragmatic, personal, social, psychological world.
In a natural theology like simantism, it is important that I exist, a person, and that I can relate to what is not-me. From this, there is relationality, and I am not alone. From this, and for other reasons, if I am a person, then the universe can be personal. There is a give-and-take between me and what is not-me that suggests that what is not-me is a person. There is an analogy between myself, who is conscious, and what is not-me, which then might ought to be seen as conscious. If I, a consciousness, choose and cause, then what I experience might ought to also be chosen and caused by a conscious person. For these reasons, I might think that I live in relationality to all that is, and that all that is is a person. But if I am not a person, then maybe it is not.
If I exist, on some level, I am awake, in a way that I am not when I somehow think that I don't exist.
Perhaps too, if I slip below the waves into non-existence, I can no longer relate to God, can no longer really be a moral person or an obedient person, for not being able to be myself, choosing. I can still go through the motions of life -- who wouldn't? I can flow away from unbearability and toward what is attractive, automatically and inevitably. But on a deeper level, I can't relate to God, and on a deeper level, what we can't or don't relate to, doesn't exist to us.
But as long as I can recognize facts, I recognize the fact that I exist.
You have real limitations, but if you can remember, you always exist. And then there is always some level on which you can be courageous, given whatever limitations you have.