It takes some effort to grasp the method of actualism, so I've linked the wiki below[1] if you're interested in exploring further (most people run away at this stage :P), but the basic method is to feel good, as a bottom-line, each and every moment again ... and sincerely explore (neither withdrawing nor psychoanalyzing) any hindrances to that feeling good until one can clearly see the silliness (whatever it is) of it preventing one from enjoying this moment (which clear seeing is sufficient to get back to feeling good). It is as simple as that (and, before you bring up any parallel, it is 180 degrees opposite to any meditation/ stoicism practices that HN is so fond of).
[1] https://github.com/ActualFreedom/home/wiki