Lawson has "big combat boots to fill" as chief of defence staff, MacKay said, referring to the job's high profile and the high regard in which his two predecessors from the army ranks, Rick Hillier and Walt Natynczyk, were held.
But as Lawson steps into those boots, this leader from the air force side of the organization will confront a changed landscape from the scene previous top generals surveyed. Buried under that are several political landmines.
Here's a look at the current state of the terrain over at National Defence headquarters, including several hot-button issues he'll have to manage.
F-35 fighter jet purchase
Within minutes of the announcement of Lawson's appointment, Ottawa was buzzing with research and retweets on everything the new top general had written and said about Canada's purchase of fighter jets to replace the CF-18s.
No surprises here: the former fighter pilot is a fan of the F-35, the stealth fighter the government announced the intention to purchase in 2010.
After months of controversy about its cost, the government has referred the entire procurement to a new Public Works secretariat tasked with reviewing and re-doing the entire thing (minus the predetermined outcome, ministers and officials are now quick to say.)
"We will continue to take our lead on the F-35 from the government," Lawson told reporters at his inaugural press conference Monday. "It will continue to contend for the replacement for the CF-18."
But when the new CDS said he'd "be providing our best advice throughout the process" he wasn't just being cautious.
"Many of the key decisions have already been made," says Kim Richard Nossal, the director of the Centre for International and Defence Policy at Queen's University. "This is something the CDS can only play a supporting role in."
"The lead on explaining this procurement has to be taken by ministers in cabinet," Nossal adds.
"He will have to tread very carefully with that file," says retired colonel Alain Pellerin from the Conference of Defence Associations, an advocacy group for Canada's defence industry.
But Pellerin does see a role for Lawson in the sell job.
"Once [the government has] a plan, they need to have somebody in place to explain it, not just from the air force but from a chief of defence who has other responsibilities to manage."
Philippe Lagassé, from the school of Public and International Affairs at the University of Ottawa, thinks much will turn on whether the air force is asked to revise its earlier statement of requirements for the replacement fighter jets.
If it does, Lawson may find himself in a position of having to defend his team's needs without causing too much political fuss.
"He needs to help reassure the government that the CDS can help in this," Lagassé says.
The F-35 may be its poster child, but military procurement generally has become a major headache for the Harper government, leading to a rare outburst of public frustration from Public Works Minister Rona Ambrose earlier this year.
From trucks to supply ships to search and rescue planes, the management of major purchases for the military has been fraught with delays and cost concerns.
As budget constraints kick in, the affordability of the military's plans can be called into question, leading to tough choices at Lawson's desk about who should be asked to sacrifice what requirements and for how long.
On top of all the things the military wants to purchase in the short and medium term, there are also the things it has to put off and make do with in the meantime, like its troubled aging submarine fleet.
"The traditional CDS mentality is just to wait for better days," says Lagassé, "but that's not a realistic option."
The 'Leslie Report'
Former Lt.-Gen. Andrew Leslie, the man once thought to be a top contender for CDS, reported back to MacKay a year ago with his prescription for "transformation" in the Canadian Forces. It called for dramatic cuts to the bureaucratic side of the military's operations so the people on the frontlines have the support and equipment they need.
That report has not yet been implemented, and Leslie was not picked for the top job. But the government still has to consider what to do with his recommendations.
The defence department is also redrafting its $490 billion "Canada First Defence Strategy" to bring the department's plans in line with the government's greater budgetary goals.
Cuts to the department's civillian work force were among the bigger line items in the 2012 budget. It was the second consecutive budget cut for defence, which until then had seen its resources double since the Conservatives took office.
"The ambition is enormous, the means are modest," Lagassé says.
In expressing confidence in Lawson's leadership, MacKay said his government's goals would "continue to be achieved."
"At end of day the main prerequisite for the chief of defence staff is that the prime minister has to be comfortable with whoever he will select," Pellerin says.
Life after Afghanistan
From Prime Minister Stephen Harper on down, there's every indication that "out means out" in Afghanistan after 2014.
How will Canada use its military down the road?
Key allies such as the United States are "rebalancing," shifting attention and resources away from Europe and NATO and toward emerging concerns in the Asia-Pacific region and the Middle East.
Supporting allies with concerns about China and managing new threats from Iran require new expertise, different equipment and new bases for staging potential operations.
Compared to other presumptive CDS candidates, Lawson has less mission command experience. When asked Monday, MacKay said the 37-year veteran has a "wealth of experience" and relevant leadership positions on his resumé.
But a lack of command experience may not matter that much for the immediate road ahead, which may not be focused on large combat missions abroad.
"We may be back to a period where we aren’t 'commanding' anything, but merely 'running things,'" Nossal says.
Recruitment, retention, retirement
Lawson's predecessors were held in high regard among the rank and file because they were perceived to be fighters on behalf of their troops. When asked about his priorities on Monday, Lawson included looking after wounded soldiers on his list.
If Lawson presides over a period of fewer missions it could mean greater uncertainty for his rank and file. Where past generals struggled to recruit in sufficient numbers to meet high operational demands in Afghanistan, Lawson may have retention challenges if a lack of missions means the military's top talent moves on.
Having taken credit for restoring Canada's military to a place of pride, it's unlikely the Harper government would then preside over a significant downsizing. But Lawson's tenure may resemble a holding pattern, particularly if the economy worsens rather than improves.
"His visions will be defined for him by whatever kind of cuts are visited upon him by government," Nossal says.