Itchy Feet

Hostel booking, checked! Address, checked! Packing list, checked! What else? What else?
It's been almost 2 years since this feet gets to touch new soil and I am excited. And nervous too... Will be going to Cambodia for 10 days in about 3 days (on the 21st Jan to be exact). The plan is to cover Phnom Penh, Siem Reap & Sihanoukville. Seems a lot and I cannot imagine how I'll survive 4km by 4km ruins.