Calling rehab "a very humbling place", Spears confessed she was "lost" and felt insecure after settling a divorce with rapper husband Kevin Federline in March.
She also humbly states, "We will never really understand or figure out life completely. That's God's job."
The 25-year-old singer has previously thanked her fans for their prayers, which have helped her during her difficult time.
She has left a short message for her fans on her website saying: "I am so blessed that you care enough about me to be concerned and will continue to live in this brighter state with all of you by my side during this trying time."
Spears added: "We are all the lights of the world and we all need to continually inspire others and look to the higher power. You are all in my prayers. Godspeed."
In her recent message, she continued to thank fans: "I am going to make mistakes everyday, and I am sure every mistake I make will probably be on CNN or 'Good Morning America.'
"I am only human people and I love you for still loving me."