She captioned the snap: 'Love my @lonelylingerie and I think I will wear it to dinner with some boots & a smile because we are all very lucky to be free.'
The Girls actress was clad in Lonely Lingerie's 'Lonely Bonnie' seafoam green bra that had nude illusion panels on the cups with scalloped edges and matching panties.
She held onto a towel rack with one hand and held her hip with the other.
It's likely that her boyfriend of three years Jack Antonoff snapped the photo, as she followed up the post with a snap of his attire for their Memorial Day celebration, writing, 'Holiday Swagger.'
The Bleachers musician looked dapper in a maroon blazer, black shirt and dark trousers.
Lena and the rocker met on a blind date in 2012 and currently live together in Brooklyn.
No doubt the 31-year-old is equally impressed with her physical progress as he is with the change in her attitude since she began a fitness program with celebrity personal trainer Tracey Anderson.
In fact, last month the comedic-actress told her fans that "it has helped with my anxiety in ways I never dreamed possible."
"To those struggling with anxiety, OCD, depression: I know it's mad annoying when people tell you to exercise, and it took me about 16 medicated years to listen. I'm glad I did," she captioned a photo of her figure in leggings and a yellow sports bra.
She added: "It ain't about the ass, it's about the brain."
On one of her most recent sessions, she shared with her Instagram fans that she had to wear ill-fitting workout gear because she forgot to bring the proper clothes.
Still, she remained undaunted and did not let it - along with balancing her career - interfere with her workout plans.
She explained: "Promised myself I would not let exercise be the first thing to go by the wayside when I got busy with Girls Season 5. Had to snag a size large bra and size small pants (wrong in myriad ways.) But do we soldier on? Yes, yes we do because we want to be a strong & happy lady #largebrasmallpantscantlose."
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- nzherald.co.nz with Daily Mail