It is difficult for many to switch gears from accumulating to withdrawal mode. The mental gymnastics can be dealt with easier IF one can detach themselves from their portfolio as part of their actual personal being and consider it as a resource, just like using one's skills to earn income is a resource. The difference really is that instead of the income coming as a result of one's personal labour, it is coming from a place of doing nothing for it (no labour) at all. The "dollars" coming into the bank account don't have physical labels attached to them.
It is easier still if one's standard of living (cash flow spend) remains, more or less, the same post-retirement as in pre-retirement, i.e. one's SWR/VPW draw per year (or annuity if the entire portfolio was annuitized) is about the same as one's pay, net of payroll burden and allocations for investment, pre-retirement. One will spend some of that cash flow differently of course, e.g. recreation and travel rather than commuting costs and business clothing, but if the dollars spent are about the same, a person shouldn't miss a beat. The real difference is social environment and the availability of way more free hours.
Not that long ago, the proceeds of an RRSP had to be annuitized when converted at age 71. If that annuity, along with CPP/DB pension provided one with cash flow that was equivalent to one's pre-retirement cash flow, the mental gymnastics making the shift would be far easier to stick handle.