Say Molly was always a little clumsy and low in confidence/high social anxiety she took up Yoga or/and Tai Chi to help with it, but just pre meeting Sherlock she got too busy to keep it up became clumsy and anxious again, between stress and guilt of not been able to tell anyone that Sherlock’s alive she MADE time to take it up again after RF.

Do whatever.

Bonus
*Regaining her confidence is why she broke up with Tom (not to settle) and she really is over Sherlock
*Sherlock using Molly’s home as a bolt hole, her going through her exercise affects him more than naked Irene