Ang sakit ng katawan ko, nahihilo ako

I'm assuming that the lawnmower you used was the manual type (not the one where you can ride it), so your body ached due to muscle fatigue. Mowing the lawn can be described as a moderate physical activity (riding one, however, is a completely different story).

The aches and pains usually felt after physical exertion is attributed to the accumulation of waste/by-products (called lactic acid) in your muscles because of the work that it did. Normally, the body has the ability to get rid of the lactic acid efficiently. However, in the setting of exercise/more strenuous physical activity, the muscles work faster and the body cannot cope with the increased lactic acid production, thus it accumulates and causes muscle aches. This peaks within the first 24 hours after the strenuous physical activity and may last for up to 3 days. You can take a pain reliever (on a full stomach) for this, if you feel that you can't tolerate the muscle aches. If it persists for more than 3 days, better consult a physician.
Since you mentioned that you mow lawns on a regular basis, might I suggest that you do stretching exercises before you start so that your muscles are limber and prepared for the work you're going to do.

Handling paints without personal protection is a big No-No. Covering your nose with a t-shirt is not enough. Most household paints (liquid or spray) contain lead, iron oxides, cadmium, pigments, and solvents like toluene & xylene among others. These chemicals can cause a variety of reactions when it gets in contact with your eyes, your skin, and your mucous membranes (including the nostrils). It can cause allergic dermatitis, drowsiness, dizziness, headaches, asthma-like symptoms, etc.

Next time, use eye goggles and a face mask which are readily available in most hardware stores. Make sure that there's adequate ventilation in the area where you plan to spray paint and ensure that there are no open flames in the area.