Fibre Care:

Fibre cushions need to be teased on a regular basis, this can be very time consuming but needs to be carried out.
If not the fibre will slowly matt together with daily compressions and eventually over time become one hard flat lump and totally lifeless.

After this has happened a very vigoure tease can revive the cushion for a while, but the lump inside is too tangled and matted to revive totally.

Teasing.
If the fibre cushion has a poly cotton cover (same as bed sheets) this can be teased okay. If it is a corovin cover, this fabric looks like tea bag material, (we don't use this fabric as standard) be very very careful as your fingers can easily pierce the cover.
Hold the cushion from both sides, push your hands together compressing the cushion, grab the fibre inside and pull away, this will tear the fibre apart inside the cushion. This will not damage the fibre but seperate the matt and revive.