I struggle to relax also. It's a difficult balance restful and productive, I find I achieve it by being loose with my internal view of productivity. For example I find watching movies or tv series as productive as it is absorbing new content, having new things to critique and analyse and even having new ammunition for when i'm forced to use my
role function.
I rationalise other things like this as well including playing games being productive for my asperations at games development, socialising being productive in maintaining potentialy useful and rewarding friendships etc.
I also find activites like cleaning and reading can be both productive and restful in the more traditional sense and exercies as well if you are loose with your defnition of restful. In reality I'm happiest working with other people on some sort of productive group project though but I think thats just the
dom.
Often being alone and having free time is very frustrating because I want to be doing something productive but I also want to relax and enjoy my free time, I found this situation is better when my free time is as the result of a sick day or some other holiday where there is no guilt associated with a lack of productivity.
The situation for me is improved when other areas of my life are going well such as being in a happy relationship, which seems to mitigate some of the need for improvement and productivity during my spare time. Although this may be because I see the time spent on the relationship as productive and so the reduced amount of free time is mine to relax *shrugs*.