Exercise already not going to plan

On Monday I decided I wanted to start exercising. I did like 10 push ups, 10-15 crunches, planked for 1 min, and lifted 5lb weights 15 times each side. I was pretty proud of myself then but now I’ve been sore for 2 days, mostly in the lower abdomen. At the time I did it it didn’t seem like I was doing that much. Like I wanted to push myself a little but I didn’t think it would make me this sore. I just tried to exercise again but it hurts too much. I’m pretty upset by it.