Wanting to control your speech implies the need to forcefully do things so stop yourself from stammering.
The unspoken message here is, you are doing something wrong and need to correct it.
On the otherhand, owning your speech is a different attitude altogether as is the unspoken message.
In general we usually want to take of what we own.
If you own your speech then you will want to look after it. Looking after implies responsibility, yet compassion and patience at the same time.