Dittli was born in Attinghausen where he attended the local schools. He later completed a teaching certificate. After working a few years in the profession he completed post-graduate studies at the Military Academy of the ETH Zurich.
Between 1978 and 1985, Dittli worked in the public school system, as a teacher. After completing the Military Academy at the ETH Zurich he worked in several positions as a senior officer of the Swiss Armed Forces. In 2000, he completed a certification in Security Policy at the NATO Defense College in Rome, Italy. In the rank of General Staff, he was then, among other positions, commander of the management course II and finally commander of the tactical training center in the higher cadre training of the Swiss Armed Forces in Kriens.
Dittli has been President of the Health Insurers Association Curafutura since January 1, 2018, succeeding Ignazio Cassis, who was then elected to the Federal Council. Dittli is also chairman of the Board of Directors of Swisslos, a member of the Sport-Toto Society and President of the VAP Association of Retailers. He is also President of the Vested Benefits Foundation of Liberty Pension AG and the 3a Pension Foundation as well as a member on several other non-profit organizations.[6]