One thing that helped for me was to treat this period as also life, rather than something I must sit through.

I still highlight dumb holidays (next week is International I Hate Cilantro Day), read by the candlelight, explore abandoned buildings, ride my bicycle around etc.

I had to delay the plans for which I have strived for many years, but I don't consider that time lost. I got to try things I wouldn't have tried otherwise, and to invest my time in different places.

When I get hit by a wave of despair (usually after they push the dates further), I do something that reaffirms this.