You ought to repent of your neglect of prayer time after time; the fact that you suffer from some medical challenges does not absolve you of your duty to pray on time as long as you are in sound mind and full control of your senses and judgment.

 

It seems your problem is that you do not take the matter of prayer seriously.

 

You ought to remember that Prayer is the most important pillar of Islam and it is the first of the duties ordained by Allah on every single messenger He sent from Adam to Muhammad. The Prophet (peace be upon him) said, “Prayer is the pivotal pillar of religion; whoever establishes it establishes the religion; whoever neglects it undermines religion.” (Ibn Hajar) Also, “whoever observes prayer diligently it would serve as a light, evidence of faith, and a means of salvation for him on the day of judgment. Whoever neglects it he will be deprived of light, evidence, and means of salvation.” (Ibn Hibban)

 

The fact that you keep on missing your prayers while being awake for one reason or another is a sign of sheer laziness or lack of motivation.

If you are too weak to stand and pray, you should sit down and pray.

 

Almighty Allah knows best.