Air carrier Captain reported the Flight Directors were not turned on which resulted in no airspeed bugs displaying during the takeoff roll. After the takeoff roll started the takeoff was rejected by the Captain and the flight returned to the gate.

Narrative

First flight of a 3-leg day on a planned 6-leg 3-day sequence. Conducted thorough briefings with all Flight Attendants and the First Officer. Must have glanced right over the Flight Director lights on preflight. During the Before Takeoff Checklist 'Flight Instruments and Bugs' Challenge; I could have sworn I saw a pink over blue bugs on the dim basic screens amidst the bright direct sunlight; and now realize I had dropped the 1 Flight Director 2 from my habitual cross check for that item; even though that isn't in the AOM. Cleared for takeoff; lined up on centerline and advanced the throttles to the second detent for a rolling flex takeoff. Did not see 'FLEX' on the FMA; and selected Takeoff Go Around to see if that would help. After seeing that did not result in 'Takeoff Go Around' either; I called 'Reject; My Aircraft' at what I thought was just shy of 80 KIAS. Max auto-braking commenced; which I attempted unsuccessfully to override with manual braking for a couple seconds. As the aircraft came to a rocking stop; I pressed the PA button and stated ' This is the Captain; remain seated; remain seated; remain seated' and the First Officer advised ATC. We taxied off the runway on X; and followed Ground's instructions to turn left on Y and hold short of XY. I made another PA stating we had an unsafe cockpit indication after applying takeoff thrust; and would need to turn to the gate for maintenance. The First Officer was first to realize the Flight Directors were off as we taxied clear of the runway; and quickly concluded my preflight oversight led to our situation. I called Dispatch connect to the Maintenance Center; who informed us a maintenance inspection would be required for any reject at or above 80 KIAS. We returned to the same departure gate where I coordinated with the #1 and Gate Agent before making the FOM DOT Extended Delay (opportunity to deplane) PA; and sent an ACARS message to Dispatch with the PA time XA:13.1. Missed Flight Director lights on preflight.2. Distracted by limited time to prepare for an impromptu vacation; devised after losing scheduled vacation to COVID illness.3. Had been trying to drop this trip for over a week; but with Chiefs only authorized to must-have Employee Off days for family emergencies; I ended up preparing as much as I could for a 7 day vacation day prior to the sequence; knowing I had a list of things to accomplish in the eight hours between the conclusion of my sequence and departing with my family for the airport. That wouldn't have been necessary if our system allowed the same credit as actual pay for SA days; a systemic problem that creates an 18-day work month. Another solution commonly available to most corporate employees in the U.S. would be converting vacation lost to COVID to sick days; and permitting the employee to convert later work days to the vacation lost. Vacation best maintains employee mental health and job satisfaction when it is dedicated to quality family time; not to quarantining at home with active COVID.1. Consider adding a 1 Flight Director 2 check to the Takeoff Data and Speeds item of the Before Takeoff Checklist.2. Make sick time credit equal to pay.3. Allow pilots who can document sick during vacation to convert days to sick and gain back vacation time balance 4. Permit must-have Employee Off days on a case by case basis without overly constraining the evaluation criteria.