I am not in the business of no pain no gain.
Exercise should leave you feeling energised rather than drained, if you have never trained before I always start at a manageable place then gradually progress. This will help you develop your strength and cardio at a steady pace.
Same goes if you turn up for class after a tough night (we have all been there) and you are already feeling a bit depleted. I will scale things down to something a bit more manageable, you will always feel a bit more you after some movement.
Starting something new can be daunting, so if you want a chat before you start a class just drop me a message.