I like the feeling when I’m working very hard. Whether that’s lifting weights, hiking, mountains, or just moving heavy things I generally enjoy that feeling of exertion.
In terms of you starting to enjoy it, the only suggestion that I would make is that the only way through is forward and keep it going until it becomes enjoyable for you. That might sound counterintuitive but ultimately little in life that’s easy is worthwhile and the effort that you’ll put in will be rewarding.