Yes you do, unless there is some legitimate medical reason for your inability to attend, in which case you may be able to delay your appointment. OWCP has every right to scheduled medical exams for you at “reasonable” intervals.
Receipt of federal disability benefits does not always mean the beneficiary is unable to work. If you can work and want to work, get your doctor's blessing and WORK!
A retired federal employee may apply for work again with the federal government and become a “re-employed annuitant”, may secure employment in the private sector, or may become self-employed.
Re-employment is a new beginning. For some it can be frightening, a reintroduction to feelings last encountered long ago and gladly forgotten. A job hunt can be intimidating, especially if you have worked in one job for most of your adult life. It can also be a time of reinvention, renewed vigor, self-discovery, triumph, and sweet surprise.
Your OPM benefit will not be reduced unless you earn a a large sum of money (80% of your date of retirement pay). While it is true that OWCP will reduce your benefit by each dollar earned, a better way to see this is that OWCP makes up any difference in pay between your date of injury federal job and any subsequent income. You will receive a ‘make-up check’ from OWCP as long as work-related disability continues.