I have been going to the gym (on and off) for about 20 years (I am in my late 30s). One thing that I have definitely established is that I do not like getting very tired and if I do work out hard, it creates an animosity and fear in my head for working out so that I am likely to dodge the next day.
One way I have countered that was to reduce my workout load to significantly below my capacity so that gym visits become actually enjoyable rather than sweltering pits of misery and pain. Under reduced schedule, I actually look forward to going in as I am not fearing the discomfort. In fact, I have realized that this approach pays better for me over time as I will lift a cumulatively higher amount of weight than if I start pushing myself but start hating and avoiding it soon.
I understand I will never be super fit because I simply refuse to endure pain but that's OK -- when I work out lazily, I still feel significant improvement over not working out at all and feel reasonably fit. So I am looking for more tips on how to even advance the workout for a lazy person. Are there any studies on how to make the workout pleasurable and painless? I believe some gain is possible without pain. Primarily I am interested in the psychology of making workout fit in your life's routine and as painless as possible.