As a claimant has the burden to establish a covered condition, a CEO who has returned to work and exercises control over the corporation cannot establish a claim for disability based on the inability to perform another management task (sales) that he deems essential for the corporation to succeed.
http://media.ca7.uscourts.gov/cgi-bin/rssExec.pl?Submit=Display&Path=Y2018/D06-21/C:17-3137:J:Barrett:aut:T:fnOp:N:2174099:S:0
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.