If you are a runner that gives up at the first difficulty, here some advice from the “Czech Locomotive”

0. Who was Emil Zátopek?

From Wikipedia:

Emil Zátopek was a Czechoslovak long-distance runner best known for winning three gold medals at the 1952 Summer Olympics in Helsinki
He won gold in the 5,000 metres and 10,000 metres runs, but his final medal came when he decided at the last minute to compete in the first marathon of his life.

Zátopek was the first runner to break the 29-minute barrier in the 10,000 metres (in 1954). 
Three years earlier, in 1951, he had broken the hour for running 20 km.

He is widely considered to be one of the greatest runners of the 20th century and was also known for his brutally tough training methods.

1. It’s never too late

If I can get better, why not? — Emil Zátopek

Emil Zátopek realized his greatest sporting challenge (the triple gold medal of Helsinki) at 30 years, a very advanced age for a wearying discipline as the distance running.

Furthermore, Zátopek had started late also his racing career: before 18 years he had never done workouts.

Yes, it may also be late to achieve certain goals, but this should not be an excuse to give up.

2. Train in always, in all conditions

It’s at the borders of pain and suffering that the men are separated from the boys. — Emil Zátopek

Zátopek ran for miles in the snow, and did it not with ultralight technical shoes: he trained with some heavy war boots.
Furthermore, in 1946 Zátopek was locked in Prague but he need to participate to his first international competition, so it decide to reach Berlin with a bicycle: 354 km along the roads devastated by the bombings of World War II.

Learn to keep his eyes fixed on your goal and no one will stop you.

3. Do not be intimidated

Are you running out of breath? Go faster! — Emil Zátopek

Zátopek ran his first marathon with the Olympic champion Jim Peters.

Halfway through the race the two athletes are paired. 
Zátopek, having no experience of such long races, asks Peters if their pace is not too high.

Although the pace is very high, Peters tries to demotivate the opponent saying that “are going too slow”.
So Emil accelerates, Peters tries to keep up but stops after a few kilometers with cramps.
Zatopek keeps his pace up to the entrance of the stadium, winning his third gold medal and breaking the previous record of 6 minutes.

4. Life is not a beauty contest

“I was not talented enough to run and smile at the same time.” — Emil Zátopek

The Zátopek running style was awful: he ran with an expression of agony on his face, the neck nestled between the shoulders, and arms moving completely uncoordinated.

His grimaces and his snorts were the object of irony of the commentators, who had nicknamed him the “Czech Locomotive”

But he won, a lot!