Go to recovery mode for changing passwd of a user

If forgot the password for a user (esp an adminstator), this is what I do. My system is Ubuntu 12.04.

1) start computer
2) push the left Shift button very quicky even before the message 'touch ESC for entering the BIOS' appears, such that we can get the grub interface
3) choose the recovery mode of my linux system
4) Then there appears several choices: "resume"... "root".., choose the choice of "root"
5) type: mount -rw -o remont /
to give the read and write permision
6)type: passwd myusername
then give the new passwords for twice
7)type: exit
8) the window of 4) appears again, then choose "resume"
then it is ok.