Related Clues:

• Walk hard carrying logs?
• Walk heavily, as if through mud
• Walk slowly and heavily
• Dug what's inert, it seems, on foot
• Participate in a forced march
• Walk with slow, heavy steps
• Intrude force in go-slow?
• Hit - hard work
• Hit hard - work hard
• Work (or walk) involving great effort
• Plod doggedly
• Work long and hard for second record
• Work hard — hard work
• Walk, as through mud
• Plod wearily