Penn Station to Islip Airport

I will be taking the LIRR from Penn Station to Islip Airport on a Sunday afternoon. I think I get off at the Ronkonkoma Station but want to know how difficult it is to get from that station to the Islip Airport?

Penn Station to Islip Airport

The airport website gives directions:

macarthurairport.com/pages/transportation.sh鈥?/a>

Penn Station to Islip Airport

Thanks!