I just recently discovered an excellent YouTube channel where you can learn chords and practice improvising in given keys. I have been using this a lot recently to practice playing keys I don’t normally play to much e.g. Cmaj and Amaj. It has the chords scrolling across the screen from right to left so you can see what chords are coming next. I noticed that although the tracks are all in the one key, there are many borrowed chords which gives it that tension here and there.
I have been practicing playing the Bossa Nova type tracks, However I good soulful one I recommend is below. You can add more colour by slightly changing keys to match some of the minor chords.