You need to make a committant to exercise
and pencil it into your schedule.
Decide which types of exercise you like to do so you have options based on the day, time available, weather, how you are feeling. Don't discount a 10 minute walk if that's all the time you have. Commit to 2 days/wk for the first 2 weeks then gradually add extra days. Start with 20-30 min increasing to 60 min 5 days/wk.