If you do not shower for 2 days the worst that will happen to you is that you begin to smell of body odor or you begin to feel sticky and icky especially if you're sweating a lot.
I had to go a week without showering before and it was awful but nothing bad happened to me and I was so relieved to be able to take a nice hot shower after my plumbing got fixed.
At 2 days you should not stink too bad unless you produce a lot of body odor and it's okay to wait 2 days to shower if you're not sweating too much or getting very dirty.
But if you get very dirty or sweat more often then you really should shower everyday at least once per day.
I personally shower twice per day to stay feeling clean and actually being clean as well.