Christina Aguilera Tells Demi Lovato She Has Missed Her 'So Very Much'

Christina Anguilera left a few words of love and encouragement on a selfie that Demi Lovato shared to Instagram on Wednesday. Lovato left rehab last month, and has been working to better herself since her drug overdose in July, Entertainment Tonight reported.

Lovato's selfie showed her healthy, glowing, makeup-free skin as she posed while practicing jiu jitsu.

"Sweaty, messy, jiu jitsu hair... #BJJ #bluebelt #nevergiveup," Lovato captioned the photo, adding a few emojis to the end.

Among a long list of adoring comments from fans, Christina Aguilera shared her own love for the "Sorry Not Sorry" singer.

"And we keep on tickin -- till the end of time -- I looooove youuuuu!" Aguilera wrote. "Can't wait to continue to heave [sic] you by side now."

In another comment, she added, "I've missed you so very much."

Aguilera's friendship with Lovato is no secret. Back in June, the "Genie in a Bottle" singer sat down for an interview with Zane Lowe on Beats 1 on Apple Music, where she spoke about Lovato's best qualities.

"She's just such a sweetheart and a real girl's girl. I love that," Aguilera said.

In May, Aguilera and Lovato collaborated on a track together, "Fall in Line," which appeared on Aguilera's album Liberation. The two artists also filmed a music video together for the song, with the video being released one week after the track initially dropped. Lovato and Aguilera performed the song together at the 2018 Billboard Awards, as well.

"It was important for me that I had somebody that could really blow. I wanted somebody that could come to play," Aguilera said about the collaboration.

The last few months have been difficult for Lovato, who was hospitalized and admitted to rehab after an apparent drug overdose in her Hollywood Hills, California, home.

Three months following her overdose, she appeared happy and healthy outside of the treatment facility, though she faced bullying online and in the media for her weight, an earlier story from the Inquisitr reported.

The singer has been spotted several times practicing jiu jitsu, a Brazilian form of self-defense. She began training long before her overdose, sharing in 2017 that she fell in love with the practice. Lovato also said that she finds jiu jitsu to be meditative, because she is constantly thinking of new ways to attack and defend, according to the Daily Mail.

Brazilian jiu jitsu focuses on hand-to-hand combat as well as on ground moves. The martial art is often depicted as a way to build character and confidence.