For most of us, running just one marathon is a big day out, so picture how it feels to run 1,000 miles in 30 days. The Guardian reports that three friends are running the equivalent of 39 marathons across eastern Europe to raise money for charity. An amazing feat worth noting.

The event underlines that the trend in ultra running that keeps going farther and farther, as more weekend warriors aim to DO:MORE. Here are five backbreaking 100 mile races.

Western States Endurance Run

One of the world’s most popular mega-marathons is the Western States 100 Mile Endurance Run. The event, which this year starts on Jun. 29 is also the oldest 100-mile race – not that they have been around long. The ultra race unofficially kicked off in 1974 during a horse race: the 1974 100-mile Tevis Cup. When local horseman Gordy Ainsleigh’s horse came to a lame stop, Ainsleigh boldly improvised by continuing on foot, finishing in 23 hours and 47 minutes. Not bad for a last second dash with less than ideal gear and clothes. Set in gold fever country, the ultra running race Ainsleigh spawned begins in Squaw Valley, California. It finishes 100.2 miles later in Auburn, California, Western States. On the way, runners climb over 18,000 ft. and descend almost 23,000 ft. before they grind over the finish line at Placer High School in Auburn.

Al Andalus Ultra-Trail

Scheduled for Jul. 8-12, the Al Andalus Ultra-Trail is a 5-stage, 140-mile ultra-marathon set in Southern Spain. Al Andalus is guaranteed to feel a bit longer than that because of the gradient. Prepare for countless long climbs that pan out as four-mile ascents and descents. The course is often technical and complicated, and over 90 percent of the Al-Andalus journey is spent on off-road mountain or desert track. Oh and let’s not forget the seething heat, the mercury is liable to rise as high as 104 degrees here. Try running up hills for over 100 miles in these conditions. Still, at the end of each day you get the chance to unwind and enjoy the ambiance of beautiful Granada Province in the heart of Andalucia, the organizers say.

The Tor des Geants

Slated for Sept. 8-15, Italy’s Tor des Geants race is pitched as freestyle – very freestyle. The organizers refuse to impose any mandatory breaks or stages on competitors. The winner is the runner who finishes the 200-mile ultra race in the shortest time, making their own decisions on when and how long to stop for rest and refreshment. Unless you are seriously seasoned, you can expect to take at least a few breaks along the high-country of the Alps. But, as with these other ultra running trails, the scenery is spectacular. The route winds along the foot of the highest Four-Thousanders in the Alps and through the Gran Paradiso Natural Park and the Mont Avic Regional Park. “All of these particular features help make this such a unique, inimitable race,” the organizers say, adding that the TDG covers an entire Italian region. Just in case you think you could breeze the 200 miles, the organizers set a time limit of 150 hours, or 6.25 days, to complete the course.

Rodopi Ultra Trail

Slated for Oct. 18-19, The Rodopi Ultra Trail (ROUT) goes on for 100 miles. The route meanders through the massive forests of the Rodopi mountain range – one of the biggest of the Balkan peninsula. ROUT’s organizers exclusively target veteran trail runners. If you want to participate in the murderously hard marathon you must possess “maximum of physical and mental endurance,” the organizers say. The organizers place an emphasis on old-school virtues: self-sufficiency and simplicity. That means minimal outside help. You have to grapple with all the challenges that the epic 100 mile race throws up alone, as you venture into remote country along tight paths lost in thick vegetation, amid land that was deserted a century ago and remains utterly uninhabited. So that you can train well for the phenomenally taxing race, the website offers a pacer calculator: “a consulting tool for constructing your race plan.” The digital mechanism somehow mysteriously calculates the degree of physical and mental exhaustion you will face as the ultra running challenge unfolds.

The JOGLE Ultra

If you think ROUT sounds hard, which it sure as hell is, try to imagine the degree of adversity you face if you enter the JOGLE Ultra. The JOGLE Ultra takes you on a wonderfully poetic route right from one end of Britain to the other – from John O’Groats to Lands End. That is an awful long way – 868 miles (count ‘em). You can see why the organizers describe the race as the “ultimate ultra-marathon”. Unless your idea of an endurance race is to canter right across Africa, JOGLE is going to hurt. You can expect some serious blisters and sneaker erosion. Last year, the lung-busting ultra race was even tougher than usual because, in traditional British style, the weather played up with a vengeance. The entrants “battled rain, torrential rain and even horizontal rain, to run through floods and the wettest April for over 100 years,” the organizers say. So you might want to pack a umbrella, if the ultra race grinds into gear again this year.