In 2010, Stefán started competing prolifically competing in competitions such as Strongman Super Series, Viking Power Challenge, Jón Páll Sigmarsson Classic and won 3rd place in 2010 Giants Live Turkey behind Žydrūnas Savickas and Brian Shaw.

He won his 2nd consecutive Iceland's Strongest Man, emerged fourth in 2010 Giants Live South Africa and also participated in 2010 London Scottish Highland Games.

But later in 2012, tragedy struck as Stefán got injured during 2012 Nordic Strongman Championships[9] and was also diagnosed with Supraventricular tachycardia[10] which took him about 3 years to recover.

Upon returning to Strongman, Stefán sustained a major injury during the frame carry event at 2016 Europe's Strongest Man and had to withdraw from competing again until full recovery.

In 2018, Stefán co-produced and starred in the documentary film 'Fullsterkur' (literally translates as 'full strength' in English) which explores the history and culture of heavy stone lifting in Iceland.