I've been smoking pot for about a year and a half now,
and I smoked few cones about 4-5 days a week
and just recently my heart has been beating fast when I smoke pot.
To me in sounds anxiety related but I'm not too sure.
I haven't smoked pot for about a month now.
Will I ever be able to smoke pot comfortably again?
Relax man. If you're been smoking for a while and took a break, could have just been the initial "shock" of smoking again. Also could be strain-related. Elevated heart levels is a very common side effect. Actually more surprised you've never experienced this before when smoking, but did your strain change? Perhaps try another strain and see what happens. Don't smoke as much next time, see what happens.
If it doesn't go away, I suggest roll with it and go work out. Hell, you're "pumped up" anyway.
(DISCLAIMER: I am not a doctor. Always consult with your doctor or physician before starting any exercise program.)