What I like about OKRs is that it really focuses on providing ways to clearly specify your goals and measure whether you are achieving them. This is also its biggest weakness, since "Key Results" that cannot be expressed as continuous, clearly measurable values will suffer. This leads to cold-seeming Initiatives like the "Connect to the girlfriend for at least six hour-long sessions." from the blog post. Well meaning no doubt, but relationship quality just doesn't lend itself to quantisation like that.

That said, I'm actually a fan of OKRs for achieving personal goals as long as you can be honest to yourself about what your Objectives actually are. (ie, if you don't really value being fit but put it on the list because you feel it is compulsory then no framework is going to provide enough motivation) In corporate settings, the incentives are typically not aligned at all and that tends to break implementation very badly. But for personal settings where you are both goal-setter and implementer it can work quite well.