I came across this publication put out by the Upper Canada Crown Lands Office, dated April 4, 1839. It states as follows:
When a person wanted to get a land grant he had to send in a petition. After a bunch of red tape if his petition was successful the person would be issued a grant and he is now a settler. The settler had to take up residence on the land and fulfill "settlement duties" which may have included clearing a portion of the land to connect to the road and to start to build a house. When this was done to the satisfaction of the Land Office agent, they owned the land.
If he did not do this the land would be forfeited.
This publication is a list of people who were awarded the land grants but who had not claimed their lots by this date. There could be several reasons for this, one of them being that the work was much harder than they were led to believe. The would-be settler could not go out and rent a backhoe or borrow a chain saw, everything had to be done by hand and perhaps with the help of a horse or an ox.
I have also given the link to the Land Grants at Library and Archive Canada for comparison.