We need to be hopeful and positive in every situation, howsoever tough it is.
A positive attitude will lead to positive results.
One example where I find all three strikes my mind and it is a Hollywood movie. In the movie Cast Away(2000), Tom Hanks crashes on an island and is stranded for four years. Soon after the crash, he accepts the truth that his chances of rescue are almost nil because of the remote location. He paints a face on a volleyball, calls it Wilson, its beautiful to watch how Tom Hanks interacts with Wilson for four full years to keep his hopes alive to see his wife and daughter whom he loves so much.
Another fine example of hope and a positive mind is another English movie 127 hours, a true story. Aron Ralston, USA met with an accident on a mountain cliff ( his hand was trapped beneath a huge boulder) for over five days. He cut his own right hand with a small dull knife when he had no means to get help. He cut his hand after 4 days, as he thought it was the only true option that would give him a real chance to live.
I am sure there would be much more examples like this in real lives of people. When faced with tough times, when faced with adversity, inner strength comes from a strong and stable mind that's filled with good thoughts and positive energy and this helps us to carry on with life.