In reply to humptydumpty:
Congrats and I'm glad you enjoyed it. It's perfectly normal to feel knackered when sport climbing - the lack of requirement to faff around with gear means that you tend to cover a lot more ground in less time than you do with trad. Sport 6a is technically much harder than the VSs and HVSs you are used to, so don't despair. The best way to train the endurance at your grade is just to climb, climb, climb. Just try to climb as many routes as you can, climb til your hands are uncurling from the holds.
Another fun thing to do with sport climbing is to try something that you know is too hard for you to onsight (say a 6b), with the goal of just getting to the top. This gives you an experience of climbing more difficult moves, in relative safety. Take an old snapgate with you so if you really can't do the moves in any way at all, you can lower off that and leave it behind.
And for the full sport climbing experience, once you've learned the moves and found all the hidden holds, you can pull the ropes and lead it in one go - this is redpointing.