Simply replace the unfilled areas such as "" and "[date]" with your information.
I'm sending a quick note to let everyone know that I will be returning to work on [date]. This leave of absence has given me the time I really needed to get better from [personal events/medical recovery/business trip/etc.] and I am now ready to get back to work.
Thank you all so much for the patience and support you have shown during the time I have been away. I am so happy about reuniting with you all again and getting back into the swing of things at [name of organization]. I look forward to seeing all of you again soon.