This is a brilliant line from a book I've got about learning russian ..... and it's dead true !
First thing then .... yes, talk to yourself. Much of language learning is repetition repetition repetition ... get used to it.
By talking to yourself you can really stick stuff into your long-term memory... after all, it's largely how we learned our first language in infancy. ,
Anyway, you all know that, even if you don't maybe do it enough...... maybe you find it embarassing.
Well, help is at hand .... these days you can talk away to yourself for as long as you like without anyone turning a hair.
As long as you are talking into your mobile phone you will be absolutely fine !
It doesn't even need to be switched on..... bonus.
You can have calm discussions about fish, long pointless anecdotes about your uncle Lionel, or huge arguments full of the most despicable insults .... all in the best Welsh you can manage