How to practice speaking to oneself?

[Antigravitas]

I'm becoming more ardent by the minute with mastering my favorite languages but at the same time I have been swamped more and more with work hours, thus leaving so much time for practicing speaking to myself at work but limited time to absorbing input (I wash cars for a living and we're not allowed to wear earphones as they're considered an occupational hazard there, so I'm left with lots of hours' opportunity to talk to myself in my target language). I obviously want to use this to my advantage but I'm worried about developing wrong habits of wrong usage of words and phrases. Any advice is welcome!

Also I find that speaking to myself does have an additional side effect of strengthening my awareness of which grammatical aspects of the language I need to work on as well as word types (verbs of motion, abstract nouns, -ing adjectives, etc.), so that I can hone on them on the spot, yet I really still worry about forming sentences with wrong structure colloquial-wise or even grammatically. How do I offset this possibility whilie still enjoying the benefits of speaking to oneself?

[smallwhite]

One thing you can do is to pick, say, 2 grammar points to practise that day, write them out on a piece of paper and keep it in your pocket, and practise those 2 grammar points that day, refering to the piece of paper as necessary.

In general, when you're speaking to yourself, you don't have to be coherent, so if you're not sure about a sentence and you fear that saying it is building bad habits, then just don't say it.

Another thing you can do is to try to recite the simple text you read the night before.

[Kraut]

I memorize complete texts like this one, after translating and practising them via bidirectional translation.

https://www.tripadvisor.es/ShowUserRevi ... Rioja.html

I recite them silently or loudly for half an hour while practising on a swing-stepper and pulling rubber bands hanging from the ceiling.
I could go for a walk for an hour and do three of these texts. Just imagining the situations and reciting the texts in my head.
I can imagine extending this practice by picking structures in my head and modifying them.

[Sumisu]

I like to practice with sentence patterns. Find a good sentence, or several sentences, in the target language for a grammatical structure you want to work on. Keep saying the sentence out loud over and over. Then start changing the words around, while keeping the pattern the same. For example:

I've finally finished writing this report.

Repeat that several times. Then change it up:

I've finally finished cleaning my room. Etc.

Depending on which languages you are learning, there may be websites with lots of good sentence patterns you can use for practicing.