How to make Page_Load event do this only once

hI , Im wondering  how to make PAge_load only do this once

protected void Page_Load(object sender, EventArgs e)
        {

            txtStart.Text = DateTime.Now.ToShortDateString();
            txtEnd.Text = DateTime.Now.AddDays(+10).ToShortDateString();
            btnReport_Click(sender, e);
any help would be appretiated;



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