Chris Moyses will step down as Lincoln City manager at the end of the season.
Moyses, 50, a former Imps player and director, initially took charge on a caretaker basis following the departure of Gary Simpson in November 2014.
"Managing a football club as well as running my own business has led to me working over 80 hours a week and that is simply not sustainable," he said.
Lincoln are 12th in the National League table, having taken two points from a possible 18 since 12 March.
Moyses announced his intention to leave after meeting club chairman Bob Dorrian, and said the decision was not taken "lightly".
"The club is in a good place and there has been a complete overhaul of the playing side," Moyses told the club website.
"Like the foundations of a house, you can't see where the strength is and whoever takes the reins will inherit a strong, decent group of players ready to challenge next season."