Unfortunately the court that sentenced you will require you to pay the full amount of restitution regardless of your mental health situation. If you fail to make timely payments, the court will convert the restitution order into a civil judgment against you and seek to attach your assets. It's unlikely however that the court would be able to garnish any funds you might receive from the government as a result of your disability - for example, SSDI payments should be safe from garnishment.
Please note that this answer does not constitute legal advice. It is merely intended to provide general information to aid the poster in finding answers to the problem posed. This answer does not create an attorney-client relationship. In most cases, it is best to contact an attorney directly to find answers to your problems.