Getting back in shape

hello I used to use this app a lot and nearly a year ago I gave birth to my daughter. Got back into exercise and went on hol. That was 6 months ago. Not done anything!! So fed up of being lazy and feeling tired all the time I went back to the gym 2 weeks ago and it was hell. Today I felt good and positive when I left and hoping my fitness will get back on track. Feeling the pain now mind