Complex sentence: Rethink (then the National Schizophrenia Fellowship) was founded in 1972 to give a voice to people affected by severe mental illness and today, with over 8,300 members, they remain determined that this voice will continue to be heard.
Split into simpler sentences: Rethink (then the National Schizophrenia Fellowship) was founded in 1972. Today, with over 8,300 members, they remain determined that this voice will continue to be heard.