As Allah says in Surah Baqarah:
Allah does not charge a soul except [with that within] its capacity. (Surah Baqarah, verse 286)
That means that you have the ability to cope with your disability. Also, our beloved prophet (peace and salawaat upon him) said:
The pen has been lifted from three: From the sleeper until he wakes
up, from the minor until he grows up, and from the insane until he
comes back to his senses or recovers. (Collected by An-Nasaa'i)
Other than alluding to the fact that insanity is treatable and recoverable, this talks about sin: the "pen being lifted" means that the person is not accountable for their actions. If they reach a sufficient level of disability, they are not liable to pray, fast, etc. because they don't have the mental capacity for doing so. So Allah, Al-Adl (the one who is ultimately just) does not hold them accountable.
Also, he (salallahu alayhi wa sallam) said in another hadith:
There is nothing (in the form of trouble) that comes to a believer
even if it is the pricking of a thorn that there is decreed for him by
Allah good or his sins are obliterated. (Saheeh Muslim)
In fact, in the case of epilepsy specifically, another hadith clarifies the reward:
A woman came once to the Prophet (Pbuh) and said: “I suffer from
severe epilepsy and parts of my body get exposed. Will you please pray
Allah for me?” The Prophet (Pbuh) said to her: “The choice is yours:
You may wish to endure it with patience and have admission into heaven
as your reward, or you may wish me to pray Allah to cure you.” She
said: “I will endure it, but some parts of my body get exposed, so
pray Allah for me not to be exposed.” The Prophet (Pbuh) prayed for
her. (Bukhari and Muslim)
In this case, specifically, a great reward was outlined for the sufferer or epilepsy. No doubt that similar rewards also apply to other afflictions and disabilities. And Allah knows best.