I can paddle for 12 hours and not get tired, and fear getting a pedal kayak because I would then be on the water 24/seven.
Definitely look into making your kayak fishing life easier by:
1. Practicing proper paddle and pacing techniques
2. Sitting in the right posture and remembering to use the hip/torso muscles to provide most of the power for your strokes
3. Invest in high-back seats and cushions
4. Choosing a lighter kayak
5. Have better hardware for loading/unloading
6. Eat and drink plenty to keep your blood~glucose level high
7. Smoke a cuban cigar (hey, look at Fidel C.)
8. Take a flask of your favorite muscle relaxant/pain reliever and sip whenever fatigued
and lastly...
9. Imagine what your life would be like without kayak fishing...
Stay with the Fleet...