Liverbirdie
Ryder Cup Winner
Pretty much how I found them and the Chris Ryan books. If you want something similar but usually with a bit of a historical/treasure hunt style try the Scott Mariani series about Ben Hope, former SAS major turned freelance kidnap specialist. A fun read and not to taxing.
if your willing to suspend a bit of belief, but with great historical context try some of the Matthew reilly books like, five greatest warriors, 3 secret cities, 6 sacred stones - the jack west novels.
Real page turners.
Ok he should have been killed 58 times in each book, but some of the ways he gets out of it are "creative" an sometimes corny, but the history aspects are good.