Maybe you have a good job, and you'd like to keep it, but you have Migraine disease, and that keeps you from showing up at the job consistently. If you're lucky, there are accommodations that your employer can make that will make it possible for you to keep on working full time. This is where the ADA comes into play, protecting your right to work with accommodations that make it possible to go on working.
If your job description, or your set of triggers, or your Migraine frequency is such that there's no way to accommodate around them, you may qualify for FMLA and be able to take 12 weeks of unpaid leave per year. At this point, you're keeping your job, but you are potentially taking a 25% cut in pay (if you spend 25% of your time on unpaid leave). This is definitely better than losing the job or going on disability for most of us.
If you need more than 25% of your time off, you may apply for disability benefits. Your company, your union or professional association, or you personally may have private disability insurance that will compensate you for a partial or total disability. This could fill in the gap between full time employment and complete disability. A few lucky people may be able to continue in their jobs part-time while collecting partial disability benefits, but this would be entirely up to your employer and your particular disability insurance plan.
If you can prove you are totally disabled, and your disability will continue for at least a year, you may qualify for Social Security Disability. If you can't work, disability is certainly better than having no income. It is an entitlement; you have worked for it and paid into the fund, and you ought to get it. However, it is a low rate of income to live on, and many people will find that, although they can't manage to work at their former job, they still don't qualify for Social Security Disability.
To gain and keep any of these benefits or entitlements, you may have to fight for them. Every employer does not happily hand us the help and accommodations we need, and it can be cold comfort to be told we have to go to a lawyer or start a lawsuit. So what can we do to take care of ourselves in case we can't stay employed full-time? If you lose the job, you still need some income.
Unfortunately, Migraine disease can have a very real impact on our careers and our earning capacity. There are plenty of people who find they cannot keep up with the schedule, or the stress, or the intellectual demands of their former job. They can't work full-time hours or regularly scheduled hours, but can still do productive work. There are plenty of people who are partly disabled, or mostly disabled, but don't qualify for disability income. They don't all have a spouse to support them, and even if they did, most families' budgets are based on two earners, not one. Let's look at some alternatives.