Well Jeff Buckley for me is one of the greatest singers I've ever heard. And the reason why is he has an amazing range amazing emotional power in his voice. And the music he put around it also just had this passion and this soul to it and this spirit to it that very few artists have and he passed at a very young age.
If you do cardio one day and the next day you can do weights do it that way. If you need to do it at night or in the morning do it that way. Whatever you need to get it done just get it done.
