Trending @Accenture; Workload Exhaustion

Since I joined the new project, when manager is on 1 week leave I need to handle all his object and mine too. Again next month he will be on leave and again workload will come upon me. No other resource is there. Giving me unachievable targets which they don't even provide kt. Being developer it sucks sometimes Not complaining but I am exhausted. I need to look for other projects. Every single day I am mentally drained. Need solution!