I often find exercising a grind. I found going to work a grind but I still did it. I find brushing my teeth a bore but I still do it. Once I started exercising and moving out of my lothful ways, I realised that exercising and trying to keep my body healthy was as important as (and in many cases more than) other things that I found time and energy to do.
I also found, as with some other things that I have to do, that if I make it fun, I'm more likely to do it. So I hum the Rocky theme when punching; I make aeroplane noises with arm circles and holds (yes, that's my inner child coming out); and I often just have some sort of story playing out in my head while I'm doing things. And if you do some exercise you really want to do, that helps, too. Purpose is important.
In my view, it doesn't really matter how much you do, just so long as you do something and you feel good while/after doing it. And experimentation is fun.