Justin Bieber Shadow Boxes Driver During London Trip With Hailey Baldwin

It's clear to see Justin Bieber's romance with Hailey Baldwin has the singer punch drunk with love ... so much so the Biebs could barely contain himself while shadow boxing during the lovers' trip to London.

Just look at how energetic Justin is in this vid ... bobbing, weaving and grinning as he playfully boxes his driver. Nothing lifts your spirits quite like love.

It all went down during Justin's trip to London with bride-to-be Hailey ... ya know, the one where they sucked face above the city before he serenaded her with an impromptu concert outside Buckingham Palace.

We're told Justin and Hailey didn't meet with any members of the Royal family ... but judging from his boxing sesh, nothing could bring Bieber down from cloud 9 -- not with Hailey by his side.

If you think you've seen Justin in the ring before ... you're right!