As with anything, progress towards a goal should be made slowly and steadily to keep momentum and motivation. If you try to do too much at once and put pressure on yourself you might not reach your short-term goals which will minimise the chance of achieving the longer-term goal. Take small steps every day, and when you feel comfortable add in another small goal.
It is important to remind yourself that this situation will not last forever. The human race has accomplished amazing and seemingly impossible feats. History is littered with wars, disease and other challenges, but we are resilient and always come through it at the other end. Keep a good balance of the activities you do to maintain your physical and mental health. Take each day as it comes, be as adaptable as possible and most importantly be forgiving of yourself. Remember: your best is good enough.