Salva now... talking about challenges and adversities...
When fleeing Sudan I faced many challenges and I found that nature can present many challenges toward humans.
"Marial was gone- vanished into the night. He would have never wandered away from the group on his own. His disappearance could only mean one thing. Lion." 
Salva and Uncle walk together through the Sudanese plains.
"Thousands maybe millions, of hungry mosquitoes that in one breath Salva could have ended up with a mouthful if he wasn't careful. And even If he was, they were everywhere- in his eyes, nose, ears, on every part of his body." 
After crossing the Nile river Salva faced the announce of lots and lots of mosquitoes.
"The first day in the desert felt like the longest day Salva ever lived through. The sun was relentless and eternal: There was neither a wisp of cloud nor whiff of breeze for relief." 
Salva walks through the rough deserts when fleeing Sudan.
Salva had to walk a long distance everyday to flee Sudan from war.
Nature can present many challenges towards humans and the challenges can be grueling and tough.