by loving Yahweh your God, by listening to His voice, and by holding fast to Him; for this is your life and the length of your days, that you may live in the land which Yahweh swore to your fathers, to Abraham, to Isaac, and to Jacob, to give them.”
Deuteronomy 30:18 I declare to you today that you shall surely perish. You will not prolong your days in the land where you are crossing the Jordan to enter and possess it.
Deuteronomy 30:19 I call heaven and earth to witness against you today, that I have set before you life and death, the blessing and the curse. So choose life in order that you may live, you and your seed,
Deuteronomy 30:20 by loving Yahweh your God, by listening to His voice, and by holding fast to Him; for this is your life and the length of your days, that you may live in the land which Yahweh swore to your fathers, to Abraham, to Isaac, and to Jacob, to give them.”
The verse centers on "loving", "yahweh", "listening", "voice", "holding", "fast", "life", and "length". It is saying that the verse draws attention to "loving" and "yahweh", so its meaning should be read from those terms before moving to application.
The prior verse says "I call heaven and earth to witness...", giving immediate footing for "loving" and "yahweh". In Deuteronomy context, the local focus is covenant, worship, and faithfulness.
A plain takeaway is to answer the verse's own emphasis on "loving" and "yahweh" with trust shaped by these words, not by a vague optimism outside the passage.