> we are at our best when we have deadlines and clear targets to reach

I'd argue we are at our best when those deadlines and clear targets are intrinsic rather than extrinsic, and that intrinsic motivation of that sort is actually more efficient than extrinsic, as it keeps you going much longer.

But yes, that's not always possible and depends greatly on your circumstances.

However, it is often much more possible than people allow themselves to think.