Каждому своя ноша тяжела

Everyone thinks he works hardest or has to put up with more difficulties than anyone else

Cf: Every horse thinks his pack heaviest (Am., Br.). Every horse thinks its /own/ sack heaviest (Br.). Every man thinks his own burden the heaviest (Am.). Every one thinks his own burden heavy (his own cross the hardest to bear, his pack heaviest) (Br.). Everyone thinks his sack heaviest (Am., Br.). То everyone his own cross is heaviest (Am.)