i got told you only have to sleep upright for 7-10 days so you should be ok! it all depends how you feel, youll no if your ready, i find it uncomfortable now lying completely flat and im 7 weeks post op i just sleep on my side which is fine! i wouldnt start back at the gym! and i deffo wouldnt do sit ups yet! i have only just started doing all that and im past 6 weeks, its not worth the risk! x