UFC heavyweight Stefan Struve returned to sparring for the first time since early in 2013 this week, as the Dutch fighter tries to work his way back from a serious heart defect.

Struve found out he has an enlarged heart and leaking aortic valve this summer, but he continues to see doctors and work on the condition. Recently, he wrote that “my heart has decreased in size” and that the leak has gone from “medium severe to minimal.”

“First time sparring since (February) of this year, finally :)” he posted on Twitter. “Timing was a bit off but it felt amazing to do what I love doing again. Not feeling anything different then before. On my (way) to that comeback!”

The 25-year-old lost to Mark Hunt in March, snapping a four-fight win streak. Struve (25-6) owns 16 submission and eight knockout wins to his credit, while all of his six defeats have come via finish.