Mihaly Czikszentmihalyi asks, "What makes a life worth living?" in this video.
When I started to read the positive psychology research I noticed that one of the experimental paradigms involves having subjects keep diaries in which they record various kinds of activities and their emotional responses to them. The idea was to identify which activities led to Czikszentmihalyi's "flow". Of course career developers nowadays use an informal version of this technique when we ask clients to discuss what they prefer to do. If you want to achieve flow, however, then you must take the time to perform this work with greater care.
Here's a new and worthwhile site that is scientifically based and meant to help its members achieve greater personal happiness which might be akin to flow: happier.com. Although it does not focus on work most of us would find it difficult to avoid career issues in finding a path towards greater happiness. In other words, aim for happiness and as part of that you will probably find a better career path. What I find most striking about it though is that the exercises this site offers attempt to influence members to identify broader goals, themes, meanings and so on. This is just what constructivist practice seeks to do and it will be interesting to see how effective the site proves to be.
(Let me mention just one concern: the language level is too high for a great many of the unemployed people that some of us see in agencies.)