Apart from boxing, what else would combine well with chess?

Figureskating.

By the way, @MervynS: Jenniffer Shahady is a professional poker player.

I believe Ice-fishing, swimming, and chess might make a good combo.

https://www.rt.com/news/324931-russia-chess-ice-swimmers/

i would think a lawyer might be witty enough to become a good chess player. me myself ice fish and find no connection.

Intimidation my great fighters is one way that it connects.

fishing with a stock

Brains and Brawn is the the idea behind chess and boxing. I think the event no longer takes place. Had a run for a couple of years.Table Tennis is popular, using the same rating system as chess.

funny thing is that i was once a former boxer before tearing my left bicept tendon , and started playing chess

sex

Tennis.

Backgammon... similar skill set.

Sex... Knight jumps queen! Pawn jumps Queen! Everybody jumps Queen!

'history of the world, part 1' -mel brooks movie quote.

scuba diving; don't you fathom?

lmao, good one!

jiu jitsu forsure

Game hunting...  Here : can you shoot a moving bear from a moving vehicle while moving a chess piece? 

duplicate bridge--both can be played at the same time and this has been done already.

How about fencing?  As in chess, you would have to look for an opening while avoiding giving your opponent an opening. 

Sheep herding. Tending to the flock is a good counter-balance to playing chess. 

crackers.