you know what grinds my gears

Im five weeks 1 day and im tired. My job is being a carer in a residential care home so it is a pretty demanding job. My work have been brilliant and said they will come and go with me. Today i had been sick since i woke right up till 5.30pm today. By 7pm i was exhausted so i had asked to go away and hour early. Boss agreed. However a staff member saud i should just suck it up cause thats what happens and get used to it. I was taken aback ad yes its early on but i am tired and sga says sge has had three its not that bad.... now why do people feel the need to dictate to what you should do? Should i be annoyed? Yes im early on but i cannot help it im on my feet 8 hours abdconstantly  moving people who weight over 10st... the heaviest being 19st