Well I've never been bored, I love it and I don't want to give it up. 33 years, of which 25 is airline flying, mainly short-haul schedule with a bit of ad hoc charter and night freighting.
The really bright, sharpest-knife-in-the-cutlery-drawer types often get bored - they think they could run the airline (probably accurately) and, funnily enough, so do the dunces. I know I don't fit the first category, and I hope I don't qualify for the second.
The tedious bits are all on the ground - standby, positioning/deadheading etc. One thing is for sure - for every 1000 hours flying in your log book, you will have 5000 hours of 'waiting'!!