What drugs are you on? Are you still on an anti-arrhythmia drug and beta blockers? Those will sap the energy right out of you.
Also I have noticed since my ablation in July as I did following my first ablation in 2009, my endurance and hearts reactive nature to exercise has changed. I am guessing it will come back in time as it did back in 2009 but I am just now starting to get back to the swing of things as I had other issues unrelated to my heart that was hindering my ability to exercise.