Joe Jonas Back Into the Swing of Things ... Ahead of Wedding

2/1/2018 7:29 AM PST

Joe Jonas is Getting Back in Shape Before His Wedding

Screw cake by the ocean -- Joe Jonas is getting into shape by the pool before his big wedding ... and it looks like his workouts are in full swing. 

Joe was seen getting his Russian kettlebell swing on Wednesday at the Bondi Icebergs Pool near Sydney, Australia -- where he seemed to be working up quite a sweat.

After his exercise, he hopped into the famous pool for a dip.

As we reported ... Joe asked girlfriend Sophie Turner to marry him this past October, and she said yes. However, a wedding date has yet to be announced.

Depending on how much time he's got -- probably a lot since 'GoT' ain't coming out 'til next year -- maybe he should consider the MMA grind again. Seemed to work wonders back then.