I will be using the diegetic sounds available in my footage for the majority of the sequence, for example when Theo is running, due to the fact that I would prefer these sounds to be more natural and add realism, as it may sound forced if I were to use Foley sounds for them. Saying this, I will also pre-record a lot of sound beforehand, such as heavy breathing, so that I would be able to increase the sound levels of it without also increasing, say, the wind. I will also record all of the speech in my sequence at a different time to filming, as the levels will be easier to adjust and produce a crisper sound, and also, crucially, my voice actors are different to my main actors.
For the main body of my sequence, I will use a non-diegetic soundtrack to play behind any speech, movement, etc, as I believe it will help set the scene and build tension. I will use the royalty-free music of Purple Planet on Sound Cloud for this, as I like their collection of tunes and have found a few eligible ones, such as Dance For Death.
I think that by using a variated selection of sounds, I can do many things at the same time, each with a different purpose, such as those mentioned above.