As someone who has/still is coping with burnout, I still find relaxing to be very difficult most of the time. I exercise now, eat better, my day job is no longer in programming, but while relaxing I still feel like I am being unproductive and that I should either get some work done or feel bad. It's gotten better, but almost 1.5 years after I really burnt out, it's still a struggle.
Having friends and family who you explain this to (and actually understand) helps immensely. You need someone who drags you into relaxation and keeps you there until you really do enjoy it and who forces you to try new things. IMO that's the best advice of this article.